Carlos Santa [Wed, 17 Aug 2016 19:30:37 +0000 (12:30 -0700)]
drm/i915: Remove .is_mobile field from platform struct
As recommended by Ville Syrjala removing .is_mobile field from the
platform struct definition for vlv and hsw+ GPUs as there's no need to
make the distinction in later hardware anymore. Keep it for older GPUs
as it is still needed for ilk-ivb.
Signed-off-by: Carlos Santa <carlos.santa@intel.com> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Carlos Santa [Wed, 17 Aug 2016 19:30:36 +0000 (12:30 -0700)]
drm/i915: Move HAS_PSR definition to platform struct definition
[patch series] Moving all GPU features to the platform struct definition
allows for
- standard place when adding new features from new platforms
- possible to see supported features when dumping struct definition
Signed-off-by: Carlos Santa <carlos.santa@intel.com> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Split out the DisplayPort and HDMI pll setup code into separate
functions and refactor the DP code that calculates the pll
so that it doesn't depend on crtc state.
This will be used for acquiring port pll when doing
upfront link training.
Jim Bride [Thu, 1 Sep 2016 22:08:10 +0000 (15:08 -0700)]
drm/i915: Split skl_get_dpll()
Split out the DisplayPort and HDMI pll setup code into separate
functions and refactor the DP code does not directly depend on
crtc state, so that the code can be used for upfront link training.
Durgadoss R [Thu, 1 Sep 2016 22:08:09 +0000 (15:08 -0700)]
drm/i915: Split bxt_ddi_pll_select()
Split out of bxt_ddi_pll_select() the logic that calculates the pll
dividers and dpll_hw_state into a new function that doesn't depend on
crtc state. This will be used for enabling the port pll when doing
upfront link training.
v2:
* Refactored code so that bxt_clk_div need not be exported (Durga)
v1:
* Rebased on top of intel_dpll_mgr.c (Durga)
* Initial version from Ander on top of intel_ddi.c
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com> Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com> Signed-off-by: Durgadoss R <durgadoss.r@intel.com> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
drm/i915: Split intel_ddi_pre_enable() into DP and HDMI versions
Split intel_ddi_pre_enable() into encoder type specific versions that
don't depend on crtc_state. The necessary parameters are passed as
function arguments. This split will be necessary for implementing DP
upfront link training.
drm/i915: Remove ddi_pll_sel from intel_crtc_state
The value of ddi_pll_sel is derived from the selection of shared dpll,
so just calculate the final value when necessary.
v2: Actually remove it from crtc state and delete remaining usages. (CI)
Reviewed-by: Durgadoss R <durgadoss.r@intel.com> Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Our current implementation of live status check (repeat 9 times
with 10ms delays between each attempt as a workaround for
buggy displays) imposes a rather serious penalty, time wise,
on intel_hdmi_detect(). Since we we already skip live status
checks on platforms before gen 7, and since we seem to have
coped quite well before the live status check was introduced
for newer platforms too, the previous behaviour is probably
preferable, at least unless someone can point to a use-case
that the live status check improves (apart from "Bspec says so".)
Signed-off-by: David Weinehall <david.weinehall@linux.intel.com> Fixes: 237ed86c693d ("drm/i915: Check live status before reading edid") Fixes: f8d03ea0053b ("drm/i915: increase the tries for HDMI hotplug live status checking")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97139
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94014 Acked-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: stable@vger.kernel.org # v4.4+ Signed-off-by: Jani Nikula <jani.nikula@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20160817124748.31208-1-david.weinehall@linux.intel.com
Lyude [Mon, 29 Aug 2016 16:31:27 +0000 (12:31 -0400)]
drm/i915/skl: Don't try to update plane watermarks if they haven't changed
i915 sometimes needs to disable planes in the middle of an atomic
commit, and then reenable them later in the same commit. Because of
this, we can't make the assumption that the state of the plane actually
changed. Since the state of the plane hasn't actually changed, neither
have it's watermarks. And if the watermarks hasn't changed then we
haven't populated skl_results with anything, which means we'll end up
zeroing out a plane's watermarks in the middle of the atomic commit
without restoring them later.
Simple reproduction recipe:
- Get a SKL laptop, launch any kind of X session
- Get two extra monitors
- Keep hotplugging both displays (so that the display configuration
jumps from 1 active pipe to 3 active pipes and back)
- Eventually underrun
Changes since v1:
- Fix incorrect use of "it's"
Changes since v2:
- Add reproduction recipe
Chris Wilson [Tue, 6 Sep 2016 14:45:38 +0000 (15:45 +0100)]
drm/i915: Remove 64b mmio write vfuncs
We don't have safe 64-bit mmio writes as they are really split into
2x32-bit writes. This tearing is dangerous as the hardware *will*
operate on the intermediate value, requiring great care when assigning.
(See, for example, i965_write_fence_reg.) As such we don't currently use
them and strongly advise not to us them. Go one step further and remove
the 64-bit write vfuncs.
v2: Add some more details to the comment about why WRITE64 is absent,
and why you need to think twice before using READ64.
Zhi Wang [Tue, 6 Sep 2016 04:04:12 +0000 (12:04 +0800)]
drm/i915: disable 48bit full PPGTT when vGPU is active
Disable 48bit full PPGTT on vGPU too for now.
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com> Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Acked-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: drm-intel-fixes@lists.freedesktop.org Signed-off-by: Jani Nikula <jani.nikula@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20160906040412.1274-3-zhenyuw@linux.intel.com
Chris Wilson [Tue, 6 Sep 2016 07:38:44 +0000 (08:38 +0100)]
drm/i915: Don't wait for a spinlock inside error capture
If we can't grab the breadcrumb's spinlock, possibly due to a driver
deadlock inside the waiters, ignore them. Like hangcheck, error
capturing must work no matter how the driver/GPU dies.
Dave Gordon [Thu, 18 Aug 2016 17:17:24 +0000 (18:17 +0100)]
drm/i915/guc: revisit GuC loader message levels
Some downgraded from DRM_ERROR() to DRM_WARN() or DRM_NOTE(),
a few upgraded from DRM_INFO() to DRM_NOTE() or DRM_WARN(),
and one eliminated completely.
v2: different permutation of levels :)
v3: convert a couple of "this shouldn't happen" messages to WARN()
Signed-off-by: Dave Gordon <david.s.gordon@intel.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Dave Gordon [Thu, 18 Aug 2016 17:17:22 +0000 (18:17 +0100)]
drm: extra printk() wrapper macros
We had only DRM_INFO() and DRM_ERROR(), whereas the underlying printk()
provides several other useful intermediate levels such as NOTICE and
WARNING. So this patch fills out the set by providing both regular and
once-only macros for each of the levels INFO, NOTICE, and WARNING, using
a common underlying macro that does all the token-pasting.
DRM_ERROR is unchanged, as it's not just a printk wrapper.
v2:
Fix whitespace, missing ## (Eric Engestrom)
Signed-off-by: Dave Gordon <david.s.gordon@intel.com> Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com> Cc: dri-devel@lists.freedesktop.org Acked-by: Dave Airlie <airlied@redhat.com> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Chris Wilson [Sat, 3 Sep 2016 06:53:43 +0000 (07:53 +0100)]
drm/i915: debugfs/i915_gem_interrupt_info does not need struct_mutex
i915_gem_interrupt_info() only looks at mmio registers, and the waiters
under a spinlock. It doesn't need struct_mutex (but does need the rpm
wakelock for mmio access). Maybe useful using get_if_notidle?
Imre Deak [Wed, 31 Aug 2016 16:13:07 +0000 (19:13 +0300)]
drm/i915/bdw: sseu: Fix sseu status parsing
Currently when checking for fused off EUs we may ignore the EU count in
an enabled slice if there is any disabled slice preceding the enabled
one (with a lower slice ID). Perhaps this can't happen in reality, but
there is no reason to have this assumption built-in, the code is clearer
without it.
Imre Deak [Wed, 31 Aug 2016 16:13:05 +0000 (19:13 +0300)]
drm/i915: sseu: Convert subslice count fields to subslice mask
In an upcoming patch we'll need the actual mask of subslices in addition
to their count, so convert the subslice_per_slice field to a mask.
Also we can easily calculate subslice_total from the other fields, so
instead of storing a cached version of this, add a helper to calculate
it.
v2:
- Use hweight8() on u8 typed vars instead of hweight32(). (Ben)
Reviewed-by: Robert Bragg <robert@sixbynine.org> (v1) Reviewed-by: Ben Widawsky <benjamin.widawsky@intel.com> (v1) Tested-by: Ben Widawsky <benjamin.widawsky@intel.com> (v1) Signed-off-by: Imre Deak <imre.deak@intel.com>
Imre Deak [Wed, 31 Aug 2016 16:13:02 +0000 (19:13 +0300)]
drm/i915: sseu: Use sseu_dev_info in device info
Move all slice/subslice/eu related properties to the sseu_dev_info
struct.
No functional change.
v2:
- s/info/sseu/ based on the new struct name. (Ben)
Reviewed-by: Robert Bragg <robert@sixbynine.org> (v1) Reviewed-by: Ben Widawsky <benjamin.widawsky@intel.com> (v1) Tested-by: Ben Widawsky <benjamin.widawsky@intel.com> (v1) Signed-off-by: Imre Deak <imre.deak@intel.com>
Imre Deak [Wed, 31 Aug 2016 16:13:01 +0000 (19:13 +0300)]
drm/i915: sseu: Move sseu_dev_status to i915_drv.h
The data in this struct is provided both by getting the
slice/subslice/eu features available on a given platform and the actual
runtime state of these same features which depends on the HW's current
power saving state.
Atm members of this struct are duplicated in sseu_dev_status and
intel_device_info. For clarity and code reuse we can share one struct
for both of the above purposes. This patch only moves the struct to the
header file, the next patch will convert users of intel_device_info to
use this struct too.
Instead of unsigned int u8 is used now, which is big enough and is used
anyway in intel_device_info.
No functional change.
v2:
- s/stat/sseu/ based on the new struct name (Ben)
David Weinehall [Fri, 2 Sep 2016 10:46:17 +0000 (13:46 +0300)]
drm/i915: Cleanup i915_param()
Rather than having a separate case for each value where we just return
a hardcoded value = 1, we lump them all together and rely on the awesome
case-fallthrough feature of C.
Fix all feature macros to pass dev_priv instead of dev while at it,
and use INTEL_GEN() instead of INTEL_INFO()->gen.
Chris Wilson [Thu, 1 Sep 2016 20:55:10 +0000 (21:55 +0100)]
drm/i915: Drop mutex around clearing error state
The error state itself is guarded by a spinlock (admittedly even that is
overkill for a single pointer!) and doesn't require us to take the
struct_mutex in the debugfs/sysfs interface. Removing the struct_mutex
removes one more potential blockage when trying to debug a deadlock.
The mentioned commit changes intel_display_crc_init to take a dev_priv,
but forgets to change the stub.
Cc: David Weinehall <david.weinehall@linux.intel.com> Fixes: 36cdd0138b7f ("drm/i915: debugfs spring cleaning") Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Reported-and-by: Kim Lidström <kim@dxtr.im> Link: http://patchwork.freedesktop.org/patch/msgid/1472116022-17598-1-git-send-email-maarten.lankhorst@linux.intel.com Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: David Weinehall <david.weinehall@linux.intel.com>
Chris Wilson [Sat, 27 Aug 2016 07:54:01 +0000 (08:54 +0100)]
drm/i915: Make for_each_engine_masked() more compact and quicker
Rather than walk the full array of engines checking whether each is in
the mask in turn, we can use the mask to jump to the right engines. This
should quicker for a sparse array of engines or mask, whilst generating
smaller code:
text data bss dec hex filename 1251010 4579 800 1256389 132bc5 drivers/gpu/drm/i915/i915.ko 1250530 4579 800 1255909 1329e5 drivers/gpu/drm/i915/i915.ko
The downside is that we have to pass in a temporary, alas no C99
iterators yet.
[P.S. Joonas doesn't like having to pass extra temporaries into the
macro, and even less that I called them tmp. As yet, we haven't found a
macro that avoids passing in a temporary that is smaller. We probably
will get C99 iterators first!]
Chris Wilson [Sat, 27 Aug 2016 07:54:00 +0000 (08:54 +0100)]
drm/i915: Tidy reporting busy status during i915_gem_retire_requests()
As we know by inspection whether any engine is still busy as we retire
all the requests, we can pass that information back via return value
rather than check again afterwards.
v2: A little more polish missed in patch splitting
Chris Wilson [Mon, 22 Aug 2016 08:03:36 +0000 (09:03 +0100)]
drm/i915: Allow the user to pass a context to any ring
With full-ppgtt, we want the user to have full control over their memory
layout, with a separate instance per context. Forcing them to use a
shared memory layout for !RCS not only duplicates the amount of work we
have to do, but also defeats the memory segregation on offer.
Chris Wilson [Fri, 26 Aug 2016 10:59:26 +0000 (11:59 +0100)]
drm/i915: Add GEN7_PCODE_MIN_FREQ_TABLE_GT_RATIO_OUT_OF_RANGE to SNB
According to the CI test machines, SNB also uses the
GEN7_PCODE_MIN_FREQ_TABLE_GT_RATIO_OUT_OF_RANGE value to report a bad
GEN6_PCODE_MIN_FREQ_TABLE request.
David Weinehall [Tue, 23 Aug 2016 09:23:56 +0000 (12:23 +0300)]
drm/i915/debugfs: Add panel delays for eDP
The eDP backlight and panel enable/disable delays are quite
useful to know when measuring time consumed by suspend/resume,
and while the information is printed to the kernel log as debug
messages, having this information in debugfs makes things easier.
Chris Wilson [Thu, 25 Aug 2016 18:05:19 +0000 (19:05 +0100)]
drm/i915: Add I915_PARAM_MMAP_GTT_VERSION to advertise unlimited mmaps
Now that we have working partial VMA and faulting support for all
objects, including fence support, advertise to userspace that it can
take advantage of unlimited GGTT mmaps.
v2: Make room in the kerneldoc for a more detailed explanation of the
limitations of the GTT mmap interface.
Lyude [Wed, 24 Aug 2016 05:48:10 +0000 (07:48 +0200)]
drm/i915/skl: Update DDB values atomically with wms/plane attrs
Now that we can hook into update_crtcs and control the order in which we
update CRTCs at each modeset, we can finish the final step of fixing
Skylake's watermark handling by performing DDB updates at the same time
as plane updates and watermark updates.
The first major change in this patch is skl_update_crtcs(), which
handles ensuring that we order each CRTC update in our atomic commits
properly so that they honor the DDB flush order.
The second major change in this patch is the order in which we flush the
pipes. While the previous order may have worked, it can't be used in
this approach since it no longer will do the right thing. For example,
using the old ddb flush order:
We have pipes A, B, and C enabled, and we're disabling C. Initial ddb
allocation looks like this:
| A | B |xxxxxxx|
Since we're performing the ddb updates after performing any CRTC
disablements in intel_atomic_commit_tail(), the space to the right of
pipe B is unallocated.
1. Flush pipes with new allocation contained into old space. None
apply, so we skip this
2. Flush pipes having their allocation reduced, but overlapping with a
previous allocation. None apply, so we also skip this
3. Flush pipes that got more space allocated. This applies to A and B,
giving us the following update order: A, B
This is wrong, since updating pipe A first will cause it to overlap with
B and potentially burst into flames. Our new order (see the code
comments for details) would update the pipes in the proper order: B, A.
As well, we calculate the order for each DDB update during the check
phase, and reference it later in the commit phase when we hit
skl_update_crtcs().
This long overdue patch fixes the rest of the underruns on Skylake.
Changes since v1:
- Add skl_ddb_entry_write() for cursor into skl_write_cursor_wm()
Changes since v2:
- Use the method for updating CRTCs that Ville suggested
- In skl_update_wm(), only copy the watermarks for the crtc that was
passed to us
Changes since v3:
- Small comment fix in skl_ddb_allocation_overlaps()
Changes since v4:
- Remove the second loop in intel_update_crtcs() and use Ville's
suggestion for updating the ddb allocations in the right order
- Get rid of the second loop and just use the ddb state as it updates
to determine what order to update everything in (thanks for the
suggestion Ville)
- Simplify skl_ddb_allocation_overlaps()
- Split actual overlap checking into it's own helper
Fixes: 0e8fb7ba7ca5 ("drm/i915/skl: Flush the WM configuration") Fixes: 8211bd5bdf5e ("drm/i915/skl: Program the DDB allocation")
[omitting CC for stable, since this patch will need to be changed for
such backports first]
Testcase: kms_cursor_legacy
Testcase: plane-all-modeset-transition Signed-off-by: Lyude <cpaul@redhat.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com> Cc: Hans de Goede <hdegoede@redhat.com> Cc: Matt Roper <matthew.d.roper@intel.com> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1471961565-28540-2-git-send-email-cpaul@redhat.com
Lyude [Wed, 24 Aug 2016 05:48:09 +0000 (07:48 +0200)]
drm/i915: Move CRTC updating in atomic_commit into it's own hook
Since we have to write ddb allocations at the same time as we do other
plane updates, we're going to need to be able to control the order in
which we execute modesets on each pipe. The easiest way to do this is to
just factor this section of intel_atomic_commit_tail()
(intel_atomic_commit() for stable branches) into it's own function, and
add an appropriate display function hook for it.
Based off of Matt Rope's suggestions
Changes since v1:
- Drop pipe_config->base.active check in intel_update_crtcs() since we
check that before calling the function
Signed-off-by: Lyude <cpaul@redhat.com> Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
[omitting CC for stable, since this patch will need to be changed for
such backports first] Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com> Cc: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Lyude <cpaul@redhat.com> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1471961565-28540-1-git-send-email-cpaul@redhat.com
Chris Wilson [Thu, 25 Aug 2016 07:23:14 +0000 (08:23 +0100)]
drm/i915: Restore lost "Initialized i915" welcome message
A side effect of removing the midlayer from driver loading was the loss
of a useful message announcing to userspace that i915 had successfully
started, e.g.:
[drm] Initialized i915 1.6.0 20160425 for 0000:00:02.0 on minor 0
Reported-by: Timo Aaltonen <tjaalton@ubuntu.com> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Fixes: 8f460e2c78f2 ("drm/i915: Demidlayer driver loading") Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: drm-intel-fixes@lists.freedesktop.org Link: http://patchwork.freedesktop.org/patch/msgid/20160825072314.17402-1-chris@chris-wilson.co.uk Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Chris Wilson [Wed, 24 Aug 2016 09:27:01 +0000 (10:27 +0100)]
drm/i915: Force RC6 restore after system resume and reset
In order for the RC6 autoenable worker to take any action, RC6 first
must be disabled. Upon resume or reset, the sw state may be stale and so
we require a forced restore.
Fixes: b7137e0cf1e5 ("drm/i915: Defer enabling rc6 til after we submit...") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@intel.com> Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20160824092701.19178-1-chris@chris-wilson.co.uk Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Chris Wilson [Wed, 24 Aug 2016 10:16:07 +0000 (11:16 +0100)]
drm/i915: Suppress DRM_ERROR for D_COMP write on Haswell
The D_COMP (render decompression) register write is followed by a status
check and another error (either that the decompression shutdown or the
lpll is enabled). Since we are followed by another, more pertinent,
error we can reduce the pcode timeout to a debug and squelch a sporadic
error message during suspend.
Chris Wilson [Wed, 24 Aug 2016 18:00:53 +0000 (19:00 +0100)]
Revert "drm/i915/fbc: Allow on unfenced surfaces, for recent gen"
This reverts commit 8678fdaf396c ("drm/i915/fbc: Allow on unfenced surfaces,
for recent gen") as Skylake has issues with unfenced FBC tracking (and
yes Skylake doesn't even enable FBC yet). Paulo would like to do a full
review of all existing workarounds to see if any more are missing prior
to allowing FBC on unfenced surfaces. In the meantime lets hope that all
framebuffers are idle and naturally fit within the mappable aperture.
drm/i915/dp: Add debug messages to print DP link training pattern
Currently we do not print the training pattern used in any of the DP link
training stages. Including this piece of information in debug messages will
help debugging.
Also, use the wrapper intel_dp_program_link_training_pattern() in
intel_dp_enable_port() instead of implementing it.
v2: Downgraded log level from error to debug (Chris)
Matthew Auld [Tue, 23 Aug 2016 15:00:44 +0000 (16:00 +0100)]
drm/i915: free intel_fb
We need to free the allocated intel_fb in the error path, not
intel_fb->base. Otherwise we risk calling kfree with a non-kmalloc'd
address, which is bound to give us grief at some point.
Reported-by: Meelis Roos <mroos@linux.ee> Fixes: 580d8ed522e0 ("drm/i915: Give encoders useful names") Reviewed-by: David Weinehall <david.weinehall@linux.intel.com> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: drm-intel-fixes@lists.freedesktop.org Signed-off-by: Jani Nikula <jani.nikula@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20160823092558.14931-1-chris@chris-wilson.co.uk
drm/i915: Create a intel_encoder_find_connector helper function.
This makes the code in intel_sanitize_encoder slightly more readable.
This was meant to be addressed in fd6bbda9c7a4, but I missed that
review comment.
Chris Wilson [Tue, 23 Aug 2016 15:50:24 +0000 (16:50 +0100)]
io-mapping.h: s/PAGE_KERNEL_IO/PAGE_KERNEL/
PAGE_KERNEL_IO is an x86-ism. Though it is used to define the pgprot_t
used for the iomapped region, it itself is just PAGE_KERNEL. On all
other arches, PAGE_KERNEL_IO is undefined so in a general header we must
refrain from using it.
v2: include pgtable for pgprot_combine()
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Fixes: cafaf14a5d8f ("io-mapping: Always create a struct to hold metadata about the io-mapping") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: linux-mm@kvack.org Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/20160823155024.22379-1-chris@chris-wilson.co.uk
Lyude [Mon, 22 Aug 2016 16:50:08 +0000 (12:50 -0400)]
drm/i915/skl: Update plane watermarks atomically during plane updates
Thanks to Ville for suggesting this as a potential solution to pipe
underruns on Skylake.
On Skylake all of the registers for configuring planes, including the
registers for configuring their watermarks, are double buffered. New
values written to them won't take effect until said registers are
"armed", which is done by writing to the PLANE_SURF (or in the case of
cursor planes, the CURBASE register) register.
With this in mind, up until now we've been updating watermarks on skl
like this:
So this patch moves all of the watermark writes into the right place;
inside of the vblank evasion where we update all of the registers for
each plane. While this patch doesn't fix everything, it does allow us to
update the watermark values in the way the hardware expects us to.
Changes since original patch series:
- Remove mutex_lock/mutex_unlock since they don't do anything and we're
not touching global state
- Move skl_write_cursor_wm/skl_write_plane_wm functions into
intel_pm.c, make externally visible
- Add skl_write_plane_wm calls to skl_update_plane
- Fix conditional for for loop in skl_write_plane_wm (level < max_level
should be level <= max_level)
- Make diagram in commit more accurate to what's actually happening
- Add Fixes:
Changes since v1:
- Use IS_GEN9() instead of IS_SKYLAKE() since these fixes apply to more
then just Skylake
- Update description to make it clear this patch doesn't fix everything
- Check if pipes were actually changed before writing watermarks
Changes since v2:
- Write PIPE_WM_LINETIME during vblank evasion
Changes since v3:
- Rebase against new SAGV patch changes
Changes since v4:
- Add a parameter to choose what skl_wm_values struct to use when
writing new plane watermarks
Changes since v5:
- Remove cursor ddb entry write in skl_write_cursor_wm(), defer until
patch 6
- Write WM_LINETIME in intel_begin_crtc_commit()
Changes since v6:
- Remove redundant dirty_pipes check in skl_write_plane_wm (we check
this in all places where we call this function, and it was supposed
to have been removed earlier anyway)
- In i9xx_update_cursor(), use dev_priv->info.gen >= 9 instead of
IS_GEN9(dev_priv). We do this everywhere else and I'd imagine this
needs to be done for gen10 as well
Changes since v7:
- Fix rebase fail (unused variable obj)
- Make struct skl_wm_values *wm const
- Fix indenting
- Use INTEL_GEN() instead of dev_priv->info.gen
Changes since v8:
- Don't forget calls to skl_write_plane_wm() when disabling planes
- Use INTEL_GEN(), not INTEL_INFO()->gen in intel_begin_crtc_commit()
Slightly less straightforward. Some of the drrs calls are done from
workers or from intel_ddi.c, pass along crtc_state when we can,
or crtc->config when we can't.
drm/i915: Remove unused loop from intel_dp_mst_compute_config
Now that conn_state is passed in as argument to compute_config, it's
guaranteed that there is a connector for the argument. The code that
looks for the connector is now dead, and completely unused. Delete it.
drm/i915: Pass crtc_state and connector_state to encoder functions
This is mostly code churn, with exception of a few places:
- intel_display.c has changes in intel_sanitize_encoder
- intel_ddi.c has intel_ddi_fdi_disable calling intel_ddi_post_disable,
and required a function change. Also affects intel_display.c
- intel_dp_mst.c passes a NULL crtc_state and conn_state to
intel_ddi_post_disable for shutting down the real encoder.
If we would pass conn_state, then conn_state->connector !=
intel_dig_port->connector and conn_state->best_encoder !=
to_intel_encoder(intel_dig_port).
We also shouldn't pass crtc_state, because in that case the
disabling sequence may potentially be different depending on
which crtc is disabled last. Nice way to introduce bugs.
No other functional changes are done, diff stat is already huge.
Each encoder type will need to be fixed to use the atomic states
separately.
drm/i915: Pass atomic state to crtc enable/disable functions
This is required for supporting nonblocking modesets. Iterating over
the connector list will no longer be allowed when we don't hold
connection_mutex, so we have to use the atomic state.
Fix disable_noatomic by populating the minimal state required to
disable a connector.
Chris Wilson [Sat, 20 Aug 2016 14:54:08 +0000 (15:54 +0100)]
drm/i915: Ignore stuck requests when considering hangs
If the engine isn't being retired (worker starvation?) then it is
possible for us to repeatedly observe that between consecutive
hangchecks the seqno on the ring to be the same and there remain
unretired requests. Ignore these completely and only regard the engine
as busy for the purpose of hang detection (not stall detection) if there
are outstanding breadcrumbs.
In recent history we have looked at using both the request and seqno as
indication of activity on the engine, but that was reduced to just
inspecting seqno in commit cffa781e5907 ("drm/i915: Simplify check for
idleness in hangcheck"). However, in commit dcff85c8443e ("drm/i915:
Enable i915_gem_wait_for_idle() without holding struct_mutex"), I made
the decision to use the new common lockless function, under the
assumption that request retirement was more frequent than hangcheck and
so we would not have a stuck busy check. The flaw there was in
forgetting that we accumulate the hang score, and so successive checks
seeing a stuck request, albeit with the GPU advancing elsewhere and so
not necessary the same stuck request, would eventually trigger the hang.
Chris Wilson [Mon, 22 Aug 2016 07:44:31 +0000 (08:44 +0100)]
drm/i915: Allow DMA pagetables to use highmem
As we never need to directly access the pages we allocate for scratch and
the pagetables, and always remap them into the GTT through the dma
remapper, we do not need to limit the allocations to lowmem i.e. we can
pass in the __GFP_HIGHMEM flag to the page allocation.
For backwards compatibility, e.g. certain old GPUs not liking highmem
for certain functions that may be accidentally mapped to the scratch
page by userspace, keep the GMCH probe as only allocating from DMA32.
Chris Wilson [Mon, 22 Aug 2016 07:44:30 +0000 (08:44 +0100)]
drm/i915: Embed the scratch page struct into each VM
As the scratch page is no longer shared between all VM, and each has
their own, forgo the small allocation and simply embed the scratch page
struct into the i915_address_space.
David Weinehall [Mon, 22 Aug 2016 10:59:31 +0000 (13:59 +0300)]
drm/i915: debugfs spring cleaning
Just like with sysfs, we do some major overhaul.
Pass dev_priv instead of dev to all feature macros (IS_, HAS_,
INTEL_, etc.). This has the side effect that a bunch of functions
now get dev_priv passed instead of dev.
All calls to INTEL_INFO()->gen have been replaced with
INTEL_GEN().
We want access to to_i915(node->minor->dev) in a lot of places,
so add the node_to_i915() helper to accommodate for this.
Finally, we have quite a few cases where we get a void * pointer,
and need to cast it to drm_device *, only to run to_i915() on it.
Add cast_to_i915() to do this.
v2: Don't introduce extra dev (Chris)
v3: Make pipe_crc_info have a pointer to drm_i915_private instead of
drm_device. This saves a bit of space, since we never use
drm_device anywhere in these functions.
Also some minor fixup that I missed in the previous version.
v4: Changed the code a bit so that dev_priv is passed directly
to various functions, thus removing the need for the
cast_to_i915() helper. Also did some additional cleanup.
v5: Additional cleanup of newly introduced changes.
David Weinehall [Mon, 22 Aug 2016 10:32:44 +0000 (13:32 +0300)]
drm/i915: pdev cleanup
In an effort to simplify things for a future push of dev_priv instead
of dev wherever possible, always take pdev via dev_priv where
feasible, eliminating the direct access from dev. Right now this
only eliminates a few cases of dev, but it also obviates that we pass
dev into a lot of functions where dev_priv would be the more obvious
choice.
v2: Fixed one more place missing in the previous patch set
David Weinehall [Mon, 22 Aug 2016 10:32:43 +0000 (13:32 +0300)]
drm/i915: i915_sysfs.c cleanup
Various cleanup for i915_sysfs.c; we now use dev_priv whenever
possible. The kdev_to_drm_minor() helper function has been
replaced by one that converts from struct device *
to struct drm_i915_private *.
We already have a seemingly identical helper (kdev_to_i915())
in i915_drv.h. But that one cannot be used here.
Unlike the version in i915_drv.h, this helper
reaches i915 through drm_minor.
v2: Rename kdev_to_i915_dm() to kdev_minor_to_i915() (Chris)
David Weinehall [Mon, 22 Aug 2016 10:32:42 +0000 (13:32 +0300)]
drm/i915: consistent struct device naming
We currently have a mix of struct device *device, struct device *kdev,
and struct device *dev (the latter forcing us to refer to
struct drm_device as something else than the normal dev).
To simplify things, always use kdev when referring to struct device.
v2: Replace the dev_to_drm_minor() macro with the inline function
kdev_to_drm_minor().
drm/i915: Fix botched merge that downgrades CSR versions.
Merge commit 5e580523d9128a4d8 reverts the version bumping parts of
commit 4aa7fb9c3c4fa0. Bump the versions again and request the specific
firmware version.
The currently recommended versions are: SKL 1.26, KBL 1.01 and BXT 1.07.
Cc: Patrik Jakobsson <patrik.jakobsson@linux.intel.com> Cc: Imre Deak <imre.deak@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97242 Cc: drm-intel-fixes@lists.freedesktop.org Fixes: 5e580523d912 ("Backmerge tag 'v4.7' into drm-next") Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1471266567-22443-1-git-send-email-maarten.lankhorst@linux.intel.com Reviewed-by: Imre Deak <imre.deak@intel.com>
Lyude [Wed, 17 Aug 2016 19:55:57 +0000 (15:55 -0400)]
drm/i915/skl: Ensure pipes with changed wms get added to the state
If we're enabling a pipe, we'll need to modify the watermarks on all
active planes. Since those planes won't be added to the state on
their own, we need to add them ourselves.
Signed-off-by: Lyude <cpaul@redhat.com> Reviewed-by: Matt Roper <matthew.d.roper@intel.com> Cc: stable@vger.kernel.org Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com> Cc: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1471463761-26796-6-git-send-email-cpaul@redhat.com
Matt Roper [Wed, 17 Aug 2016 19:55:55 +0000 (15:55 -0400)]
drm/i915/gen9: Only copy WM results for changed pipes to skl_hw
When we write watermark values to the hardware, those values are stored
in dev_priv->wm.skl_hw. However with recent watermark changes, the
results structure we're copying from only contains valid watermark and
DDB values for the pipes that are actually changing; the values for
other pipes remain 0. Thus a blind copy of the entire skl_wm_values
structure will clobber the values for unchanged pipes...we need to be
more selective and only copy over the values for the changing pipes.
This mistake was hidden until recently due to another bug that caused us
to erroneously re-calculate watermarks for all active pipes rather than
changing pipes. Only when that bug was fixed was the impact of this bug
discovered (e.g., modesets failing with "Requested display configuration
exceeds system watermark limitations" messages and leaving watermarks
non-functional, even ones initiated by intel_fbdev_restore_mode).
Changes since v1:
- Add a function for copying a pipe's wm values
(skl_copy_wm_for_pipe()) so we can reuse this later
Fixes: 734fa01f3a17 ("drm/i915/gen9: Calculate watermarks during atomic 'check' (v2)") Fixes: 9b6130227495 ("drm/i915/gen9: Re-allocate DDB only for changed pipes") Signed-off-by: Matt Roper <matthew.d.roper@intel.com> Signed-off-by: Lyude <cpaul@redhat.com> Reviewed-by: Matt Roper <matthew.d.roper@intel.com> Cc: stable@vger.kernel.org Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com> Cc: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1471463761-26796-4-git-send-email-cpaul@redhat.com
Lyude [Wed, 17 Aug 2016 19:55:54 +0000 (15:55 -0400)]
drm/i915/skl: Add support for the SAGV, fix underrun hangs
Since the watermark calculations for Skylake are still broken, we're apt
to hitting underruns very easily under multi-monitor configurations.
While it would be lovely if this was fixed, it's not. Another problem
that's been coming from this however, is the mysterious issue of
underruns causing full system hangs. An easy way to reproduce this with
a skylake system:
- Get a laptop with a skylake GPU, and hook up two external monitors to
it
- Move the cursor from the built-in LCD to one of the external displays
as quickly as you can
- You'll get a few pipe underruns, and eventually the entire system will
just freeze.
After doing a lot of investigation and reading through the bspec, I
found the existence of the SAGV, which is responsible for adjusting the
system agent voltage and clock frequencies depending on how much power
we need. According to the bspec:
"The display engine access to system memory is blocked during the
adjustment time. SAGV defaults to enabled. Software must use the
GT-driver pcode mailbox to disable SAGV when the display engine is not
able to tolerate the blocking time."
The rest of the bspec goes on to explain that software can simply leave
the SAGV enabled, and disable it when we use interlaced pipes/have more
then one pipe active.
Sure enough, with this patchset the system hangs resulting from pipe
underruns on Skylake have completely vanished on my T460s. Additionally,
the bspec mentions turning off the SAGV with more then one pipe enabled
as a workaround for display underruns. While this patch doesn't entirely
fix that, it looks like it does improve the situation a little bit so
it's likely this is going to be required to make watermarks on Skylake
fully functional.
This will still need additional work in the future: we shouldn't be
enabling the SAGV if any of the currently enabled planes can't enable WM
levels that introduce latencies >= 30 µs.
Changes since v11:
- Add skl_can_enable_sagv()
- Make sure we don't enable SAGV when not all planes can enable
watermarks >= the SAGV engine block time. I was originally going to
save this for later, but I recently managed to run into a machine
that was having problems with a single pipe configuration + SAGV.
- Make comparisons to I915_SKL_SAGV_NOT_CONTROLLED explicit
- Change I915_SAGV_DYNAMIC_FREQ to I915_SAGV_ENABLE
- Move printks outside of mutexes
- Don't print error messages twice
Changes since v10:
- Apparently sandybridge_pcode_read actually writes values and reads
them back, despite it's misleading function name. This means we've
been doing this mostly wrong and have been writing garbage to the
SAGV control. Because of this, we no longer attempt to read the SAGV
status during initialization (since there are no helpers for this).
- mlankhorst noticed that this patch was breaking on some very early
pre-release Skylake machines, which apparently don't allow you to
disable the SAGV. To prevent machines from failing tests due to SAGV
errors, if the first time we try to control the SAGV results in the
mailbox indicating an invalid command, we just disable future attempts
to control the SAGV state by setting dev_priv->skl_sagv_status to
I915_SKL_SAGV_NOT_CONTROLLED and make a note of it in dmesg.
- Move mutex_unlock() a little higher in skl_enable_sagv(). This
doesn't actually fix anything, but lets us release the lock a little
sooner since we're finished with it.
Changes since v9:
- Only enable/disable sagv on Skylake
Changes since v8:
- Add intel_state->modeset guard to the conditional for
skl_enable_sagv()
Changes since v7:
- Remove GEN9_SAGV_LOW_FREQ, replace with GEN9_SAGV_IS_ENABLED (that's
all we use it for anyway)
- Use GEN9_SAGV_IS_ENABLED instead of 0x1 for clarification
- Fix a styling error that snuck past me
Changes since v6:
- Protect skl_enable_sagv() with intel_state->modeset conditional in
intel_atomic_commit_tail()
Changes since v5:
- Don't use is_power_of_2. Makes things confusing
- Don't use the old state to figure out whether or not to
enable/disable the sagv, use the new one
- Split the loop in skl_disable_sagv into it's own function
- Move skl_sagv_enable/disable() calls into intel_atomic_commit_tail()
Changes since v4:
- Use is_power_of_2 against active_crtcs to check whether we have > 1
pipe enabled
- Fix skl_sagv_get_hw_state(): (temp & 0x1) indicates disabled, 0x0
enabled
- Call skl_sagv_enable/disable() from pre/post-plane updates
Changes since v3:
- Use time_before() to compare timeout to jiffies
Changes since v2:
- Really apply minor style nitpicks to patch this time
Changes since v1:
- Added comments about this probably being one of the requirements to
fixing Skylake's watermark issues
- Minor style nitpicks from Matt Roper
- Disable these functions on Broxton, since it doesn't have an SAGV
Lyude [Wed, 17 Aug 2016 19:55:53 +0000 (15:55 -0400)]
drm/i915/gen6+: Interpret mailbox error flags
In order to add proper support for the SAGV, we need to be able to know
what the cause of a failure to change the SAGV through the pcode mailbox
was. The reasoning for this is that some very early pre-release Skylake
machines don't actually allow you to control the SAGV on them, and
indicate an invalid mailbox command was sent.
This also might come in handy in the future for debugging.
Changes since v1:
- Add functions for interpreting gen6 mailbox error codes along with
gen7+ error codes, and actually interpret those codes properly
- Renamed patch to reflect new behavior
Signed-off-by: Lyude <cpaul@redhat.com> Cc: Matt Roper <matthew.d.roper@intel.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: stable@vger.kernel.org Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1471463761-26796-2-git-send-email-cpaul@redhat.com
[mlankhorst: -ENOSYS -> -ENXIO for checkpatch]
Paulo Zanoni [Wed, 17 Aug 2016 19:41:44 +0000 (16:41 -0300)]
drm/i915: Call intel_fbc_pre_update() after pinning the new pageflip
intel_fbc_pre_update() depends upon the new state being already pinned
in place in the Global GTT (primarily for both fencing which wants both
an offset and a fence register, if assigned). This requires the call to
intel_fbc_pre_update() be after intel_pin_and_fence_fb() - but commit e8216e502aca ("drm/i915/fbc: call intel_fbc_pre_update earlier during
page flips") moved the code way too much up in its attempt to call it
before the page flip.
v2 (from Paulo):
- Point the original bad commit.
- Add a comment to maybe prevent further regressions.
Fixes: e8216e502aca ("drm/i915/fbc: call intel_fbc_pre_update earlier...") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com> Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Patrik Jakobsson <patrik.jakobsson@linux.intel.com> Cc: drm-intel-fixes@lists.freedesktop.org Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Link: http://patchwork.freedesktop.org/patch/msgid/1471462904-842-1-git-send-email-paulo.r.zanoni@intel.com Cc: stable@vger.kernel.org
Daniel Vetter [Mon, 22 Aug 2016 08:55:22 +0000 (10:55 +0200)]
drm/i915: Ensure consistent control flow __i915_gem_active_get_rcu
This issue here is (I think) purely theoretical, since a compiler
would need to be especially foolish to recompute the value of
i915_gem_request_completed right after it was already used. Hence the
additional barrier() is also not really a restriction.
But I believe this to be at least permissible, and since our rcu
trickery is a beast it's worth to annotate all the corner cases.
Chris proposed to instead just wrap a READ_ONCE around
request->fence.seqno in i915_gem_request_completed. But that has a
measurable impact on code size, and everywhere we hold a full
reference to the underlying request it's also not needed. And
personally I'd like to have just enough barriers and locking needed
for correctness, but not more - it makes it much easier in the future
to understand what's going on.
Since the busy ioctl has now fully embraced it's races there's no
point annotating it there too. We really only need it in
active_get_rcu, since that function _must_ deliver a correct snapshot
of the active fences (and not chase something else).
Chris Wilson [Mon, 22 Aug 2016 07:44:29 +0000 (08:44 +0100)]
drm/i915: Stop marking the unaccessible scratch page as UC
Since by design, if not entirely by practice, nothing is allowed to
access the scratch page we use to background fill the VM, then we do not
need to ensure that it is coherent between the CPU and GPU.
set_pages_uc() does a stop_machine() after changing the PAT, and that
significantly impacts upon context creation throughput.
Chris Wilson [Fri, 19 Aug 2016 15:54:28 +0000 (16:54 +0100)]
drm/i915: Use remap_io_mapping() to prefault all PTE in a single pass
Very old numbers indicate this is a 66% improvement when remapping the
entire object for fence contention - due to the elimination of
track_pfn_insert and its strcmp.
Chris Wilson [Fri, 19 Aug 2016 15:54:26 +0000 (16:54 +0100)]
io-mapping: Always create a struct to hold metadata about the io-mapping
Currently, we only allocate a structure to hold metadata if we need to
allocate an ioremap for every access, such as on x86-32. However, it
would be useful to store basic information about the io-mapping, such as
its page protection, on all platforms.
Chris Wilson [Fri, 19 Aug 2016 15:54:24 +0000 (16:54 +0100)]
drm/i915/fbc: Don't set an illegal fence if unfenced
If the frontbuffer doesn't have an associated fence, it will have a
fence reg of -1. If we attempt to OR in this register into the FBC
control register we end up setting all control bits, oops!
Chris Wilson [Fri, 19 Aug 2016 15:54:23 +0000 (16:54 +0100)]
drm/i915: Flush delayed fence releases after reset
What I never hit in testing, but Mika immediately did, was a GPU hang
with a pending fence release (where a tiled object has been changed by
the user to be untiled, and the update has not yet been committed to the
fence register). As the stride/tiling is 0, this causes a divide-by-zero
error when trying to write the new fence parameters:
Reported-by: Mika Kuoppala <mika.kuoppala@intel.com> Fixes: 49ef5294cda2 ("drm/i915: Move fence tracking from object to vma") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@intel.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20160819155428.1670-1-chris@chris-wilson.co.uk
Dave Gordon [Fri, 19 Aug 2016 14:23:42 +0000 (15:23 +0100)]
drm/i915: Reattach comment, complete type specification
In the recent patch bc3d674 drm/i915: Allow userspace to request no-error-capture upon ...
the final version moved the flags and the associated #defines around
so they were adjacent; unfortunately, they ended up between a comment
and the thing (hw_id) to which the comment applies :(
So this patch reshuffles the comment and subject back together.
Also, as we're touching 'hw_id', let's change it from just 'unsigned'
to a fully-specified 'unsigned int', because some code checking tools
(including checkpatch) object to plain 'unsigned'.