Chris Wilson [Sat, 31 Dec 2016 11:20:09 +0000 (11:20 +0000)]
drm/i915: Move assert of page pin vs bind count into i915_vma_unbind
The read of the page pin count and the bind count are unordered,
presenting races in the assert and it firing off incorrectly. Prevent
this by restricting the assert to the vma bind/unbind routines where we
have local cpu ordering between the two.
drm/i915: Add dpll entrypoint for dumping hw state
Remove the IS_PLATFORM() macros from intel_dump_pipe_config() and split
that logic in platform specific implementations inside the dpll code,
accessed through a platform independent interface.
The documentation for most of the non-static members and structs were
missing. Fix that.
v2: Fix typos (Durga)
v3: Rebase.
Fix make docs warnings.
Document more.
v4: capitilize CRTC; say that the prepare hook is a nop if the DPLL is
already enabled; link to struct intel_dpll_hw_state from @hw_state
field in struct intel_shared_dpll_state; reorganize DPLL flags; link
intel_shared_dpll_state to other structs and functions. (Daniel)
drm/i915: Rename intel_shared_dpll_commit() to _swap_state()
The function intel_shared_dpll_commit() performs the equivalent of
drm_atomic_helper_swap_state() for the shared dpll state, which is not
handled by the helpers. So make it do a full swap of the state and
rename it for consistency.
While the details of getting a shared dpll are wrapped by
intel_get_shared_dpll(), the release was still hand rolled into the
modeset code. Fix that by creating an entry point for releasing the
pll and move that code there.
drm/i915: re-use computed offset bias for context pin
The context has to obey the same offset requirements as the ring,
so we can re-use the same bias value we computed for the ring instead of
unconditionally using GUC_WOPCM_TOP.
drm/i915: request ring to be pinned above GUC_WOPCM_TOP
GuC will validate the ring offset and fail if it is in the
[0, GUC_WOPCM_TOP) range. The bias is conditionally applied only
if GuC loading is enabled (we can't check for guc submission enabled as
in other cases because HuC loading requires this fix).
Note that the default context is processed before enable_guc_loading is
sanitized, so we might still apply the bias to its ring even if it is
not needed.
v2: compute the value during ctx init and pass it to
intel_ring_pin (Chris), updated commit message
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com> Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com> Cc: Anusha Srivatsa <anusha.srivatsa@intel.com> Cc: Michał Winiarski <michal.winiarski@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1482537382-28584-1-git-send-email-daniele.ceraolospurio@intel.com Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
As the fence may be signaled concurrently from an interrupt on another
device, it is possible for the list of requests on the timeline to be
modified as we walk it. Take both (the context's timeline and the global
timeline) locks to prevent such modifications.
Fixes: 80b204bce8f2 ("drm/i915: Enable multiple timelines") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Cc: <drm-intel-fixes@lists.freedesktop.org> Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161223145804.6605-10-chris@chris-wilson.co.uk
Chris Wilson [Fri, 23 Dec 2016 14:57:59 +0000 (14:57 +0000)]
drm/i915: Assert that the partial VMA fits within the object
When creating a partial VMA assert that it first fits with the parent
object, and that if it covers the whole of the parent a normal view was
created instead.
Chris Wilson [Fri, 23 Dec 2016 14:57:58 +0000 (14:57 +0000)]
drm/i915: Silence allocation failure during sg_trim()
As trimming the sg table is merely an optimisation that gracefully fails
if we cannot allocate a new table, we do not need to report the failure
either.
Chris Wilson [Fri, 23 Dec 2016 14:57:57 +0000 (14:57 +0000)]
drm/i915: Don't clflush before release phys object
When we teardown the backing storage for the phys object, we copy from
the coherent contiguous block back to the shmemfs object, clflushing as
we go. Trying to clflush the invalid sg beforehand just oops and would
be redundant (due to it already being coherent, and clflushed
afterwards).
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: <drm-intel-fixes@lists.freedesktop.org> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161223145804.6605-3-chris@chris-wilson.co.uk
Chris Wilson [Fri, 23 Dec 2016 14:57:56 +0000 (14:57 +0000)]
drm/i915: Repeat flush of idle work during suspend
The idle work handler is self-arming - if it detects that it needs to
run again it will queue itself from its work handler. Take greater care
when trying to drain the idle work, and double check that it is flushed.
The free worker has a similar issue where it is armed by an RCU task
which may be running concurrently with us.
This should hopefully help with the sporadic WARN_ON(dev_priv->gt.awake)
from i915_gem_suspend.
v2: Reuse drain_freed_objects.
v3: Don't try to flush the freed objects from the shrinker, as it may be
underneath the struct_mutex already.
v4: do while and comment upon the excess rcu_barrier in drain_freed_objects
Chris Wilson [Fri, 23 Dec 2016 14:57:55 +0000 (14:57 +0000)]
drm/i915: Break after walking all GGTT vma in bump_inactive_ggtt
Since commit db6c2b4151f2 ("drm/i915: Store the vma in an rbtree under
the object") the vma are once again sorted into GGTT first, then ppGTT
so that the typical case of walking the GGTT vma can stop as soon as we
find a non-ppGTT. Apply that optimisation.
Hans de Goede [Thu, 1 Dec 2016 20:29:13 +0000 (21:29 +0100)]
drm/i915/dsi: Move disable pll call outside of clear_device_ready()
On enable intel_dsi_enable() directly calls intel_enable_dsi_pll(),
make intel_dsi_disable() also directly call intel_disable_dsi_pll(),
rather then hiding the call in intel_dsi_clear_device_ready(),
no functional changes.
Ville Syrjälä [Wed, 7 Dec 2016 17:28:12 +0000 (19:28 +0200)]
drm/i915: Disable L2 cache clock gating on 830 when using the overlay
BSpec says:
"Overlay Clock Gating Must be Disabled: Overlay & L2 Cache clock gating
must be disabled in order to prevent device hangs when turning off overlay.SW
must turn off Ovrunit clock gating (6200h) and L2 Cache clock gating (C8h)."
We only turned off the overlay clock gating (due to lack of docs I
presume). After a bit of experimentation it looks like the the magic
C8h register lives in the PCI config space of device 0, and the magic
bit appears to be bit 2. Or at the very least this eliminates the GPU
death after MI_OVERLAY_OFF.
L2 clock gating seems to save ~80mW, so let's keep it on unless we need
to actually use the overlay.
Also let's move the OVRUNIT clock gating to the same place since we can,
and 845 supposedly doesn't need it.
Ville Syrjälä [Wed, 7 Dec 2016 17:28:06 +0000 (19:28 +0200)]
drm/i915: Fix the overlay frontbuffer tracking
Do the overlay frontbuffer tracking properly so that it matches
the state of the overlay on/off/continue requests.
One slight problem is that intel_frontbuffer_flip_complete()
may get delayed by an arbitrarily liong time due to the fact that
the overlay code likes to bail out when a signal occurs. So the
flip may not get completed until the ioctl is restarted. But fixing
that would require bigger surgery, so I decided to ignore it for now.
Ville Syrjälä [Wed, 7 Dec 2016 17:28:03 +0000 (19:28 +0200)]
drm/i915: Fix oops in overlay due to frontbuffer tracking
The vma will be NULL if the overlay was previously off, so
dereferencing it will oops. Check for NULL before doing that.
Cc: stable@vger.kernel.org Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Fixes: 9b3b7841b86d ("drm/i915/overlay: Use VMA as the primary tracker for images") Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1481131693-27993-2-git-send-email-ville.syrjala@linux.intel.com Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Ville Syrjälä [Wed, 7 Dec 2016 17:56:47 +0000 (17:56 +0000)]
drm/i915: Fix oopses in the overlay code due to i915_gem_active stuff
The i915_gem_active stuff doesn't like a NULL ->retire hook, but
the overlay code can set it to NULL. That obviously ends up oopsing.
Fix it by introducing a new helper to assign the retirement callback
that will switch out the NULL function pointer with
i915_gem_retire_noop.
Cc: stable@vger.kernel.org Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Fixes: 0d9bdd886f29 ("drm/i915: Convert intel_overlay to request tracking") Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Link: http://patchwork.freedesktop.org/patch/msgid/20161207175647.10018-1-chris@chris-wilson.co.uk
Ville Syrjälä [Tue, 20 Dec 2016 15:39:02 +0000 (17:39 +0200)]
drm/i915: Move the min_pixclk[] handling to the end of readout
Trying to determine the pixel rate of the pipe can't be done until we
know the clock, which means it can't be done until the encoder
.get_config() hooks have been called. So let's move the min_pixclk[]
stuff to the end of intel_modeset_readout_hw_state() when we actually
have gathered all the required infromation.
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Mika Kahola <mika.kahola@intel.com> Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com> Fixes: 565602d7501a ("drm/i915: Do not acquire crtc state to check clock during modeset, v4.") Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161220153902.15621-1-ville.syrjala@linux.intel.com Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com> Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Ville Syrjälä [Tue, 20 Dec 2016 16:51:17 +0000 (18:51 +0200)]
drm/i915: Force VDD off on the new power seqeuencer before starting to use it
Apparently some VLV BIOSen like to leave the VDD force bit enabled
even for power seqeuncers that aren't properly hooked up to any
port. That will result in a imbalance in the AUX power domain
refcount when we stat to use said power sequencer as edp_panel_vdd_on()
will not grab the power domain reference if it sees that the VDD is
already on.
To fix this let's make sure we turn off the VDD force bit when we
initialize the power sequencer registers. That is, unless it's
being done from the init path since there we are actually
initializing the registers for the current power sequencer and
we don't want to turn VDD off needlessly as that would require
waiting for the power cycle delay before we turn it back on.
This fixes the following kind of warnings:
WARNING: CPU: 0 PID: 123 at ../drivers/gpu/drm/i915/intel_runtime_pm.c:1455 intel_display_power_put+0x13a/0x170 [i915]()
WARN_ON(!power_domains->domain_use_count[domain])
...
v2: Fix typos in comment (David)
Cc: stable@vger.kernel.org Cc: Matwey V. Kornilov <matwey.kornilov@gmail.com> Tested-by: Matwey V. Kornilov <matwey.kornilov@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98695 Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161220165117.24801-1-ville.syrjala@linux.intel.com Reviewed-by: David Weinehall <david.weinehall@linux.intel.com>
Imre Deak [Wed, 21 Dec 2016 10:17:24 +0000 (12:17 +0200)]
drm/i915/ddi: Rely on VBT DDI port info for eDP detection
There is at least one APL based system using port A in DP mode
(connecting to an on-board DP->VGA adaptor). Atm we'll configure port A
unconditionally as eDP which is incorrect in this case. Fix this by
relying on the VBT DDI port 'internal port' flag instead on all ports on
DDI platforms. For now chicken out from using VBT for port A before
GEN9.
v2:
- Move the DDI port info lookup to intel_bios_is_port_edp() (David, Jani)
- Use the DDI port info on all DDI platforms starting from port B.
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: David Weinehall <david.weinehall@linux.intel.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (v1) Reviewed-by: David Weinehall <david.weinehall@linux.intel.com> Signed-off-by: Imre Deak <imre.deak@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1482315444-24750-1-git-send-email-imre.deak@intel.com
Elaine Wang [Mon, 19 Dec 2016 10:19:05 +0000 (18:19 +0800)]
drm/i915: Check num_pipes before initializing audio component
when num_pipes is zero, it indicates there is no display and HDMI
audio doesn't exist.
v2: Move the check from caller to callee for consistency.
Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Signed-off-by: Elaine Wang <elaine.wang@intel.com> Reviewed-by: Jani Nikula <jani.nikula@intel.com> Signed-off-by: Jani Nikula <jani.nikula@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1482142746-21663-1-git-send-email-elaine.wang@intel.com
Paulo Zanoni [Thu, 15 Dec 2016 13:23:55 +0000 (11:23 -0200)]
drm/i915: fully apply WaSkipStolenMemoryFirstPage
Don't even tell the mm allocator to handle the first page of stolen on
the affected platforms. This means that we won't inherit the FB in
case the BIOS decides to put it at the start of stolen. But the BIOS
should not be putting it at the start of stolen since it's going to
get corrupted. I suppose the bug here is that some pixels at the very
top of the screen will be corrupted, so it's not exactly easy to
notice.
We have confirmation that the first page of stolen does actually get
corrupted, so I really think we should do this in order to avoid any
possible future headaches, even if that means losing BIOS framebuffer
inheritance. Let's not use the HW in a way it's not supposed to be
used.
Notice that now ggtt->stolen_usable_size won't reflect the ending
address of the stolen usable range anymore, so we have to fix the
places that rely on this. To simplify, we'll just use U64_MAX.
v2: don't even put the first page on the mm (Chris)
v3: drm_mm_init() takes size instead of end as argument (Ville)
v4: add a comment explaining the reserved ranges (Chris)
use 0 for start and U64_MAX for end when possible (Chris)
Paulo Zanoni [Wed, 14 Dec 2016 14:55:37 +0000 (12:55 -0200)]
drm/i915: skip the first 4k of stolen memory on everything >= gen8
BSpec got updated and this workaround is now listed as standard
required programming for all subsequent projects. This is confirmed to
fix Skylake screen flickering issues (probably caused by the fact that
we initialized a ring in the first page of stolen, but I didn't 100%
confirm this theory).
v2: this is the patch that fixes the screen flickering, document it.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94605 Cc: stable@vger.kernel.org Tested-by: Dominik Klementowski <dominik232@gmail.com> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com> Acked-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/1481727338-9901-1-git-send-email-paulo.r.zanoni@intel.com
Chris Wilson [Mon, 19 Dec 2016 12:43:46 +0000 (12:43 +0000)]
drm/i915: Add a test that we terminate the trimmed sgtable as expected
In commit 0c40ce130e38 ("drm/i915: Trim the object sg table"), we expect
to copy exactly orig_st->nents across and allocate the table thusly.
The copy loop should therefore end with the new_sg being NULL.
Chris Wilson [Mon, 19 Dec 2016 12:43:45 +0000 (12:43 +0000)]
drm/i915: Fallback to single PAGE_SIZE segments for DMA remapping
If we at first do not succeed with attempting to remap our physical
pages using a coalesced scattergather list, try again with one
scattergather entry per page. This should help with swiotlb as it uses a
limited buffer size and only searches for contiguous chunks within its
buffer aligned up to the next boundary - i.e. we may prematurely cause a
failure as we are unable to utilize the unused space between large
chunks and trigger an error such as:
i915 0000:00:02.0: swiotlb buffer is full (sz: 1630208 bytes)
Reported-by: Juergen Gross <jgross@suse.com> Tested-by: Juergen Gross <jgross@suse.com> Fixes: 871dfbd67d4e ("drm/i915: Allow compaction upto SWIOTLB max segment size") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Imre Deak <imre.deak@intel.com> Cc: <drm-intel-fixes@lists.freedesktop.org> Link: http://patchwork.freedesktop.org/patch/msgid/20161219124346.550-1-chris@chris-wilson.co.uk Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Chris Wilson [Tue, 20 Dec 2016 10:40:03 +0000 (10:40 +0000)]
drm/i915/breadcrumbs: s/container_of/rb_entry/
In keeping with commit f802cf7e0986 ("drm/i915/debugfs: use
rb_entry()"), convert the primary user of the rbtrees over to using
rb_entry rather than the equivalent container_of.
Rodrigo Vivi [Mon, 19 Dec 2016 19:05:47 +0000 (11:05 -0800)]
drm/i915: Simplify gem stolen initialization.
Let's take usage of IS_LP to simplify the gem stolen
initialization as suggest by Tvrtko.
Also assume that all new LP platforms follows the chv+
and others bdw+.
v2: Remove the wrong commit message about bxt and glk. (Ander)
Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com> Cc: Imre Deak <imre.deak@intel.com> Cc: Mika Kuoppala <mika.kuoppala@intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com> Link: http://patchwork.freedesktop.org/patch/msgid/1482174347-24911-1-git-send-email-rodrigo.vivi@intel.com
Rodrigo Vivi [Sun, 18 Dec 2016 21:36:27 +0000 (13:36 -0800)]
drm/i915: Rename get stolen functions for LP platforms chv+
gen8 is used for both Broadwell and Cherryview but this
function here is only Cherryview and all next atom LP platforms.
So let's rename it to avoid confusion as suggested by Ville.
Ville Syrjälä [Wed, 14 Dec 2016 18:00:23 +0000 (20:00 +0200)]
drm/i915: Prevent PPS stealing from a normal DP port on VLV/CHV
VLV apparently gets upset if the PPS for a pipe currently driving an
external DP port gets used for VDD stuff on another eDP port. The DP
port falls over and fails to retrain when this happens, leaving the
user staring at a black screen.
Let's fix it by also tracking which pipe is driving which DP/eDP port.
We'll track this under intel_dp so that we'll share the protection
of the pps_mutex alongside the pps_pipe tracking, since the two
things are intimately related.
I had plans to reduce the protection of pps_mutex to cover only eDP
ports, but with this we can't do that. Well, for for VLV/CHV at least.
For other platforms it should still be possible, which would allow
AUX communication to occur in parallel for multiple DP ports.
v2: Drop stray crap from a comment (Imre)
Grab pps_mutex when clearing active_pipe
Fix a typo in the commit message
v3: Make vlv_active_pipe() static
Chris Wilson [Sun, 18 Dec 2016 15:37:24 +0000 (15:37 +0000)]
drm/i915: Swap if(enable_execlists) in i915_gem_request_alloc for a vfunc
A fairly trivial move of a matching pair of routines (for preparing a
request for construction) onto an engine vfunc. The ulterior motive is
to be able to create a mock request implementation.
Chris Wilson [Sun, 18 Dec 2016 15:37:23 +0000 (15:37 +0000)]
drm/i915/execlists: Request the kernel context be pinned high
PIN_HIGH is an expensive operation (in comparison to allocating from the
hole stack) unsuitable for frequent use (such as switching between
contexts). However, the kernel context should be pinned just once for
the lifetime of the driver, and here it is appropriate to keep it out of
the mappable range (in order to maximise mappable space for users).
Chris Wilson [Sun, 18 Dec 2016 15:37:22 +0000 (15:37 +0000)]
drm/i915: Mark the shadow gvt context as closed
As the shadow gvt is not user accessible and does not have an associated
vm, we can mark it as closed during its construction. This saves leaking
the internal knowledge of i915_gem_context into gvt/.
Chris Wilson [Sun, 18 Dec 2016 15:37:21 +0000 (15:37 +0000)]
drm/i915: Simplify releasing context reference
A few users only take the struct_mutex in order to release a reference
to a context. We can expose a kref_put_mutex() wrapper in order to
simplify these users, and optimise taking of the mutex to the final
unref.
Chris Wilson [Sun, 18 Dec 2016 15:37:20 +0000 (15:37 +0000)]
drm/i915: Unify active context tracking between legacy/execlists/guc
The requests conversion introduced a nasty bug where we could generate a
new request in the middle of constructing a request if we needed to idle
the system in order to evict space for a context. The request to idle
would be executed (and waited upon) before the current one, creating a
minor havoc in the seqno accounting, as we will consider the current
request to already be completed (prior to deferred seqno assignment) but
ring->last_retired_head would have been updated and still could allow
us to overwrite the current request before execution.
We also employed two different mechanisms to track the active context
until it was switched out. The legacy method allowed for waiting upon an
active context (it could forcibly evict any vma, including context's),
but the execlists method took a step backwards by pinning the vma for
the entire active lifespan of the context (the only way to evict was to
idle the entire GPU, not individual contexts). However, to circumvent
the tricky issue of locking (i.e. we cannot take struct_mutex at the
time of i915_gem_request_submit(), where we would want to move the
previous context onto the active tracker and unpin it), we take the
execlists approach and keep the contexts pinned until retirement.
The benefit of the execlists approach, more important for execlists than
legacy, was the reduction in work in pinning the context for each
request - as the context was kept pinned until idle, it could short
circuit the pinning for all active contexts.
We introduce new engine vfuncs to pin and unpin the context
respectively. The context is pinned at the start of the request, and
only unpinned when the following request is retired (this ensures that
the context is idle and coherent in main memory before we unpin it). We
move the engine->last_context tracking into the retirement itself
(rather than during request submission) in order to allow the submission
to be reordered or unwound without undue difficultly.
And finally an ulterior motive for unifying context handling was to
prepare for mock requests.
v2: Rename to last_retired_context, split out legacy_context tracking
for MI_SET_CONTEXT.
Chris Wilson [Sun, 18 Dec 2016 15:37:19 +0000 (15:37 +0000)]
drm/i915: Move intel_lrc_context_pin() to avoid the forward declaration
Just a simple move to avoid a forward declaration, though the diff likes
to present itself as a move of intel_logical_ring_alloc_request_extras()
in the opposite direction.
Matthew Auld [Tue, 13 Dec 2016 20:32:22 +0000 (20:32 +0000)]
drm/i915: convert to using range_overflows
Convert some of the obvious hand-rolled ranged overflow sanity checks to
our shiny new range_overflows macro.
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Suggested-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Matthew Auld <matthew.auld@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161213203222.32564-4-matthew.auld@intel.com Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
In a number places we hand-roll the overflow sanity check for ranges, so
roll that into single macro, conceived by Chris, along with its typed
variant.
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Suggested-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Matthew Auld <matthew.auld@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161213203222.32564-3-matthew.auld@intel.com Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Matthew Auld [Tue, 13 Dec 2016 20:32:20 +0000 (20:32 +0000)]
drm/i915: move vma sanity checking into i915_vma_bind
If we move the sanity checking from gen8_alloc_va_range_3lvl and
gen6_alloc_va_range into i915_vma_bind, we will increase our coverage to
now both callbacks. We also convert each WARN_ON over to a GEM_WARN_ON.
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Suggested-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Matthew Auld <matthew.auld@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161213203222.32564-2-matthew.auld@intel.com Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Matthew Auld [Tue, 13 Dec 2016 20:32:19 +0000 (20:32 +0000)]
drm/i915: introduce GEM_WARN_ON
In a similar spirit to GEM_BUG_ON we now also have GEM_WARN_ON, with the
simple goal of expressing warnings which are truly insane, and so are
only really useful for CI where we have some abusive tests.
v2:
- use BUILD_BUG_ON_INVALID for !DEBUG_GEM
- clarify commit message
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Suggested-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Matthew Auld <matthew.auld@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161213203222.32564-1-matthew.auld@intel.com Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Tvrtko Ursulin [Fri, 16 Dec 2016 13:18:42 +0000 (13:18 +0000)]
drm/i915: Fix use after free in logical_render_ring_init
Commit 3b3f1650b1ca ("drm/i915: Allocate intel_engine_cs
structure only for the enabled engines") introduced the
dynanically allocated engine instances and created an
potential use after free scenario in logical_render_ring_init
where lrc_destroy_wa_ctx_obj could be called after the engine
instance has been freed.
This can only happen during engine setup/init error handling
which luckily does not happen ever in practice.
Fix is to not call lrc_destroy_wa_ctx_obj since it would have
already been executed from the preceding engine cleanup.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Fixes: 3b3f1650b1ca ("drm/i915: Allocate intel_engine_cs structure only for the enabled engines") Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Link: http://patchwork.freedesktop.org/patch/msgid/1481894322-2145-1-git-send-email-tvrtko.ursulin@linux.intel.com
udelay_range(1, 2) is inefficient and as discussions with Jani Nikula
<jani.nikula@linux.intel.com> unnecessary here. This replaces this
tight setting with a relaxed delay of min=20 and max=50 which helps
the hrtimer subsystem optimize timer handling.
udelay_range(2, 3) is inefficient and as discussions with Jani Nikula
<jani.nikula@linux.intel.com> unnecessary here. This replaces this
tight setting with a relaxed delay of min=20 and max=50. which helps
the hrtimer subsystem optimize timer handling.
Paulo Zanoni [Tue, 13 Dec 2016 20:57:44 +0000 (18:57 -0200)]
drm/i915: disable PSR by default on HSW/BDW
We've been ignoring the poor bugzilla reporters that say PSR causes
system lockups and all other sorts of problems. The earliest bug
report is from April, so I think we can use the "revert the offending
commit if no fixes are presented within 8 months" rule here.
Fixes: 9b58e352b463 ("drm/i915: Enable PSR by default on Haswell and Broadwell.")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97602
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97515
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96736
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96704
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96569
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=95176
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94985 Cc: <stable@vger.kernel.org> # v4.6+ Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Jim Bride <jim.bride@linux.intel.com> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com> Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com> Acked-by: Jani Nikula <jani.nikula@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1481662664-18986-1-git-send-email-paulo.r.zanoni@intel.com
Mika Kuoppala [Wed, 14 Dec 2016 12:26:20 +0000 (14:26 +0200)]
drm/i915: Fix setting of boost freq tunable
For limiting the max frequency of gpu, the max freq tunable
is not enough to hard limit the max gap. We now have also per
client boost max freq. When this tunable was introduced,
it was mistakenly made read only. Allow user to gain control by
setting it writable.
Fixes: 29ecd78d3b79 ("drm/i915: Define a separate variable and control for RPS waitboost frequency") Cc: <stable@vger.kernel.org> # v4.9+ Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@intel.com> Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1481718380-9170-1-git-send-email-mika.kuoppala@intel.com
Jani Nikula [Tue, 13 Dec 2016 11:10:59 +0000 (13:10 +0200)]
drm/i915: simplify check for I915G/I945G in bit 6 swizzling detection
Commit c9c4b6f6c283 ("drm/i915: fix swizzle detection for gen3") added a
complicated check for I915G/I945G. Pineview and other gen3 devices match
IS_MOBILE() anyway. Simplify.
Daniel Vetter [Tue, 13 Dec 2016 19:54:14 +0000 (20:54 +0100)]
drm/i915: tune down the fast link training vs boot fail
It's been unfixed since a while and no one is immediately working on
this. And we have the FIXME already. And now also a task in the DP
team's backlog.
Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: stable@vger.kernel.org Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
References: https://lists.freedesktop.org/archives/intel-gfx/2016-July/101951.html Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[danvet: Adjust comment per Ville's feedback.] Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161213195414.28923-1-daniel.vetter@ffwll.ch
Manasi Navare [Sat, 10 Dec 2016 00:22:50 +0000 (16:22 -0800)]
drm/i915: Move all the DP compliance data to a separate struct
This patch does not change anything functionally, just cleans up
the DP compliance related variables and stores them all together
in a separate struct intel_dp_compliance. There is another struct
intel_dp_compliance_data to store all the test data. This makes it easy to
reset the compliance variables through a memset instead of
individual resetting.
v2:
* Removed functional changes for EDID (Jani Nikula)
Manasi Navare [Fri, 9 Dec 2016 03:05:12 +0000 (19:05 -0800)]
drm/i915: Find fallback link rate/lane count
If link training fails, then we need to fallback to lower
link rate first and if link training fails at RBR, then
fallback to lower lane count.
This function finds the next lower link rate/lane count
value after link training failure and limits the max
link_rate and lane_count values to these fallback values.
v7:
* Remove unnecessary intializations and remove redundant
call to intel_dp_common_rates (Jani Nikula)
v6:
* Cap the max link rate and lane count to the max
values obtained during fallback link training (Daniel Vetter)
v5:
* Start the fallback at the lane count value passed not
the max lane count (Jani Nikula)
v4:
* Remove the redundant variable link_train_failed
v3:
* Remove fallback_link_rate_index variable, just obtain
that using the helper intel_dp_link_rate_index (Jani Nikula)
v2:
Squash the patch that returns the link rate index (Jani Nikula)
Acked-by: Tony Cheng <tony.cheng@amd.com> Acked-by: Harry Wentland <harry.wentland@amd.com> Cc: Ville Syrjala <ville.syrjala@linux.intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Daniel Vetter <daniel.vetter@intel.com> Signed-off-by: Manasi Navare <manasi.d.navare@intel.com> Reviewed-by: Jani Nikula <jani.nikula@intel.com> Signed-off-by: Jani Nikula <jani.nikula@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1481252712-12925-1-git-send-email-manasi.d.navare@intel.com
Manasi Navare [Tue, 6 Dec 2016 00:27:36 +0000 (16:27 -0800)]
drm/i915: Compute sink's max lane count/link BW at Hotplug
Sink's capabilities are advertised through DPCD registers and get
updated only on hotplug. So they should be computed only once in the
long pulse handler and saved off in intel_dp structure for the use
later. For this reason two new fields max_sink_lane_count and
max_sink_link_bw are added to intel_dp structure.
This also simplifies the fallback link rate/lane count logic
to handle link training failure. In that case, the max_sink_link_bw
and max_sink_lane_count can be reccomputed to match the fallback
values lowering the sink capabilities due to link train failure.
Jani Nikula [Mon, 5 Dec 2016 07:30:34 +0000 (09:30 +0200)]
drm/i915/bxt: add bxt dsi gpio element support
Request the GPIO by index through the consumer API. For now, use a quick
hack to store the already requested ones, simply because I have no idea
whether this actually works or not, and I have no way to test it.
v2 by Mika: switch *NULL* to *"panel"* when requesting gpio for MIPI/DSI
panel.
Chris Wilson [Fri, 9 Dec 2016 15:05:55 +0000 (15:05 +0000)]
drm/i915: Retire before attempting to evict from the active lists
Some object retain an extra pin whilst they are active (e.g. contexts).
This excludes them from being considered for eviction unless we idle the
GPU. If before we look at the active list, we retire beforehand we can
hopefully remove a few excess pins and reduce the amount of searching
required.
Chris Wilson [Wed, 7 Dec 2016 13:34:11 +0000 (13:34 +0000)]
drm/i915: Reorder phys backing storage release
In commit a4f5ea64f0a8 ("drm/i915: Refactor object page API"), I
reordered the object->pages teardown to be more friendly wrt to a
separate obj->mm.lock. However, I overlooked the phys object and left it
with a dangling use-after-free of its phys_handle. Move the allocation
of the phys handle to get_pages and it release to put_pages to prevent
the invalid access and to improve symmetry.
v2: Add commentary about always aligning to page size.
Testcase: igt/drv_selftest/objects Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Fixes: a4f5ea64f0a8 ("drm/i915: Refactor object page API") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161207133411.8028-1-chris@chris-wilson.co.uk
drm/i915/psr: report psr2 hw enabled from psr2_ctl
For PSR2 , as per spec, PSR2_CTL bit 31 to be set.
for psr1, bit 31 in SRD_CTL to be set. Reporting
"HW Enabled & Active bit" status for psr2 from SRD_CTL
gives wrong status.
Robert Bragg [Wed, 7 Dec 2016 21:40:33 +0000 (21:40 +0000)]
drm/i915/perf: More documentation hooked to i915.rst
This adds a 'Perf' section to i915.rst with the following sub sections:
- Overview
- Comparison with Core Perf
- i915 Driver Entry Points
- i915 Perf Stream
- i915 Perf Observation Architecture Stream
- All i915 Perf Internals
v2:
section headers in i915.rst (Daniel Vetter)
missing symbol docs + other fixups (Matthew Auld)
Imre Deak [Mon, 5 Dec 2016 16:27:38 +0000 (18:27 +0200)]
drm/i915/gen9: Fix PCODE polling during SAGV disabling
According to the previous patch, it's possible atm that we call
intel_do_sagv_disable() only once during the 1ms period and time out if
that call fails. As opposed to this the spec says that we need to keep
retrying this request for a 1ms duration, so let's do this similarly to
the CDCLK change notification request.
v4-5:
- Rebased on the reply_mask, reply change.
v6:
- Remove w/s change. (Lyude)
- Rebased on the timeout_base argument change.
Cc: Lyude <cpaul@redhat.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Fixes: 656d1b89e5ff ("drm/i915/skl: Add support for the SAGV, fix underrun hangs") Signed-off-by: Imre Deak <imre.deak@intel.com> Reviewed-by: Lyude <lyude@redhat.com> (v4) Link: http://patchwork.freedesktop.org/patch/msgid/1480955258-26311-2-git-send-email-imre.deak@intel.com
drm/i915: Wait up to 3ms for the pcu to ack the cdclk change request on SKL
increased the timeout to match the spec, but we still see a timeout on
at least one SKL. A CDCLK change request following the failed one will
succeed nevertheless.
I could reproduce this problem easily by running kms_pipe_crc_basic in a
loop. In all failure cases _wait_for() was pre-empted for >3ms and so in
the worst case - when the pre-emption happened right after calculating
timeout__ in _wait_for() - we called skl_cdclk_wait_for_pcu_ready() only
once which failed and so _wait_for() timed out. As opposed to this the
spec says to keep retrying the request for at most a 3ms period.
To fix this send the first request explicitly to guarantee that there is
3ms between the first and last request. Though this matches the spec, I
noticed that in rare cases this can still time out if we sent only a few
requests (in the worst case 2) _and_ PCODE is busy for some reason even
after a previous request and a 3ms delay. To work around this retry the
polling with pre-emption disabled to maximize the number of requests.
Also increase the timeout to 10ms to account for interrupts that could
reduce the number of requests. With this change I couldn't trigger
the problem.
v2:
- Use 1ms poll period instead of 10us. (Chris)
v3:
- Poll with pre-emption disabled to increase the number of request
attempts. (Ville, Chris)
- Factor out a helper to poll, it's also needed by the next patch.
v4:
- Pass reply_mask, reply to skl_pcode_request(), instead of assuming the
reply is generic. (Ville)
v5:
- List the request specific timeout values as code comment. (Ville)
v6:
- Try the poll first with preemption enabled.
- Add code comment about first request being queued by PCODE. (Art)
- Add timeout_base_ms argument. (Ville)
v7:
- Clarify code comment about first queued request. (Chris)
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Art Runyan <arthur.j.runyan@intel.com> Cc: <stable@vger.kernel.org> # v4.2- : 3b2c171 : drm/i915: Wait up to 3ms Cc: <stable@vger.kernel.org> # v4.2- Fixes: 5d96d8afcfbb ("drm/i915/skl: Deinit/init the display at suspend/resume")
Reference: https://bugs.freedesktop.org/show_bug.cgi?id=97929
Testcase: igt/kms_pipe_crc_basic/suspend-read-crc-pipe-B Signed-off-by: Imre Deak <imre.deak@intel.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Link: http://patchwork.freedesktop.org/patch/msgid/1480955258-26311-1-git-send-email-imre.deak@intel.com
Jani Nikula [Wed, 7 Dec 2016 20:48:09 +0000 (22:48 +0200)]
drm/i915: distinguish G33 and Pineview from each other
Pineview deserves to use its own platform enum (which was already added,
unused, previously). IS_G33() no longer matches Pineview, and gets
replaced by IS_G33() || IS_PINEVIEW() or equivalent. Pineview is no
longer an outlier among platform definitions.
Mahesh Kumar [Thu, 1 Dec 2016 15:49:37 +0000 (21:19 +0530)]
drm/i915/skl+: change WM calc to fixed point 16.16
This patch changes Watermak calculation to fixed point calculation.
Problem with current calculation is during plane_blocks_per_line
calculation we divide intermediate blocks with min_scanlines and
takes floor of the result because of integer operation.
hence we end-up assigning less blocks than required. Which leads to
flickers.
Changes since V1:
- Add fixed point data type as per Paulo's review
Changes since V2:
- use fixed_point instead of fp_16_16
Changes since V3:
- rebase
Changes since V4 (from Paulo):
- My original renaming suggestion was misunderstood, so implement it
- Simplify fixed_16_16_to_u32 implementation
- Fix indentation
Mahesh Kumar [Thu, 1 Dec 2016 15:49:34 +0000 (21:19 +0530)]
drm/i915/bxt: IPC WA for Broxton
Display Workarounds #1135
If IPC is enabled in BXT, display underruns are observed.
WA: The Line Time programmed in the WM_LINETIME register should be
half of the actual calculated Line Time.
Programmed Line Time = 1/2*Calculated Line Time
Changes since V1:
- Add Workaround number in commit & code
Changes since V2 (from Paulo):
- Bikeshed white space and make the WA tag look like the others
Mahesh Kumar [Thu, 1 Dec 2016 15:49:33 +0000 (21:19 +0530)]
drm/i915/skl: Add variables to check x_tile and y_tile
This patch adds variable to check for X_tiled & y_tiled planes, instead
of always checking against framebuffer-modifiers.
Changes:
- Created separate patch as per Paulo's comment
- Added x_tiled variable as well
Changes since V2:
- Incorporate Paulo's comments
- Rebase
Changes since V3 (from Paulo):
- Bikeshed indentation
Hans de Goede [Thu, 1 Dec 2016 20:29:09 +0000 (21:29 +0100)]
drm/i915/dsi: Fix chv_exec_gpio disabling the GPIOs it is setting
Set the CHV_GPIO_GPIOEN bit when updating GPIOs from chv_exec_gpio.
Fixes: a0a6d4ffd2ad ("drm/i915/dsi: add support for gpio elements on CHV") Cc: stable@vger.kernel.org Cc: Jani Nikula <jani.nikula@intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161201202925.12220-3-hdegoede@redhat.com Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Hans de Goede [Fri, 2 Dec 2016 15:01:28 +0000 (16:01 +0100)]
drm/i915/dsi: Fix swapping of MIPI_SEQ_DEASSERT_RESET / MIPI_SEQ_ASSERT_RESET
Looking at the ADF code from the Android kernel sources for a
cherrytrail tablet I noticed that it is calling the
MIPI_SEQ_ASSERT_RESET sequence from the panel prepare hook.
Until commit b1cb1bd29189 ("drm/i915/dsi: update reset and power sequences
in panel prepare/unprepare hooks") the mainline i915 code was doing the
same. That commits effectively swaps the calling of MIPI_SEQ_ASSERT_RESET /
MIPI_SEQ_DEASSERT_RESET.
Looking at the naming of the sequences that is the right thing to do,
but the problem is, that the old mainline code and the ADF code was
actually calling the right sequence (tested on a cube iwork8 air tablet),
and the swapping of the calling breaks things.
This breakage was likely not noticed in testing because on cherrytrail,
currently chv_exec_gpio ends up disabling the gpio pins rather then
setting them (this is fixed in the next patch in this patch-set).
This commit fixes the swapping by fixing MIPI_SEQ_ASSERT/DEASSERT_RESET's
places in the enum defining them, so that their (new) names match their
actual use.
Changes in v2:
-Add a comment to the enum explaining that the assert/reassert names
are swapped in the spec
Fixes: b1cb1bd29189 ("drm/i915/dsi: update reset and power sequences...") Cc: Jani Nikula <jani.nikula@intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Acked-by: Jani Nikula <jani.nikula@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161202150128.29871-1-hdegoede@redhat.com Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Robert Bragg [Thu, 1 Dec 2016 17:21:52 +0000 (17:21 +0000)]
drm/i915/perf: use DRM_DEBUG for userspace issues
Avoid using DRM_ERROR for conditions userspace can trigger with a bad
config when opening a stream or from not reading data in a timely
fashion (whereby the OA buffer fills up). These conditions are tested
by i-g-t which treats error messages as failures if using the test
runner. This wasn't an issue while the i915-perf igt tests were being
run in isolation.
One message relating to seeing a spurious zeroed report was changed to
use DRM_NOTE instead of DRM_ERROR. Ideally this warning shouldn't be
seen, but it's not a serious problem if it is. Considering that the
tail margin mechanism is only a heuristic it's possible we might see
this from time to time.
Ville Syrjälä [Mon, 5 Dec 2016 14:13:28 +0000 (16:13 +0200)]
drm/i915: Protect DSPARB registers with a spinlock
Each DSPARB register can house bits for two separate pipes, hence
we must protect the registers during reprogramming so that parallel
FIFO reconfigurations happening simultaneosly on multiple pipes won't
corrupt each others values.
We'll use a new spinlock for this instead of the wm_mutex since we'll
have to move the DSPARB programming to happen from the vblank evade
critical section, and we can't use mutexes in there.
v2: Document why we use a spinlock instead of a mutex (Maarten)
projects / linux-beck.git / log