Ben Widawsky [Mon, 17 Oct 2011 22:51:54 +0000 (15:51 -0700)]
drm/i915: Remove early exit on i915_gpu_idle
[Description from: Daniel Vetter]
I've just discussed this quickly with Chris on irc and it's probably
best to just kill the list_empty early bailout. gpu_idle isn't a
fastpath, so who cares. One candidate where we emit commands to the ring
without adding anything onto these lists is e.g. pageflip. There are
probably more.
Signed-off-by: Ben Widawsky <ben@bwidawsk.net> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Keith Packard <keithp@keithp.com>
David Woodhouse [Mon, 17 Oct 2011 22:51:53 +0000 (15:51 -0700)]
intel-iommu: Export a flag indicating that the IOMMU is used for iGFX.
We really don't want this to work in the general case; device drivers
*shouldn't* care whether they are behind an IOMMU or not. But the
integrated graphics is a special case, because the IOMMU and the GTT are
all kind of smashed into one and generally horrifically buggy, so it's
reasonable for the graphics driver to want to know when the IOMMU is
active for the graphics hardware.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Ben Widawsky <ben@bwidawsk.net> Signed-off-by: Keith Packard <keithp@keithp.com>
David Woodhouse [Mon, 17 Oct 2011 22:51:52 +0000 (15:51 -0700)]
intel-iommu: Workaround IOTLB hang on Ironlake GPU
To work around a hardware issue, we have to submit IOTLB flushes while
the graphics engine is idle. The graphics driver will (we hope) go to
great lengths to ensure that it gets that right on the affected
chipset(s)... so let's not screw it over by deferring the unmap and
doing it later. That wouldn't be very helpful.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Ben Widawsky <ben@bwidawsk.net> Signed-off-by: Keith Packard <keithp@keithp.com>
Daniel Vetter [Sat, 17 Sep 2011 18:55:46 +0000 (20:55 +0200)]
drm/i915: drop KM_USER0 argument to k(un)map_atomic
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Keith Packard <keithp@keithp.com>
For the !HAVE_ATOMIC_IOMAP case the stub functions did not call
pagefault_disable/_enable. The i915 driver relies on the map
actually being atomic, otherwise it can deadlock with it's own
pagefault handler in the gtt pwrite fastpath.
This is exercised by gem_mmap_gtt from the intel-gpu-toosl gem
testsuite.
v2: Chris Wilson noted the lack of an include.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=38115 Cc: stable@kernel.org Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Keith Packard <keithp@keithp.com>
Chris Wilson [Wed, 14 Sep 2011 12:14:28 +0000 (14:14 +0200)]
drm/i915: Defend against userspace creating a gem object with size==0
We currently only round up the userspace size to the next page. We
assume that userspace hasn't made a mistake and requested a zero-length
gem object and all through our internal code we then presume that every
object is backed by at least a single page. Fix that oversight and
report EINVAL back to userspace if they try to create a zero length
object.
[danvet: This fixes tests/gem_bad_length]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Ben Widawsky <ben@bwidawsk.net> Signed-off-by: Keith Packard <keithp@keithp.com>
Daniel Vetter [Mon, 12 Sep 2011 19:30:02 +0000 (21:30 +0200)]
drm/i915: simplify swapin/out swizzle checking a bit
Use the helper function already employed by the pwrite/pread
functions.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Keith Packard <keithp@keithp.com>
Daniel Vetter [Thu, 8 Sep 2011 12:00:22 +0000 (14:00 +0200)]
drm/i915: properly cancel rps_work on module unload v2
The rps disabling code wasn't properly cancelling outstanding work
items. Also add a comment that explains why we're not racing with
the work item that could unmask interrupts - that piece of code
confused me quite a bit.
v2: Ben Widawsky pointed out that the first patch would deadlock
(and a few lesser problems). All corrected.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Ben Widawsky <ben@bwidawsk.net> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Keith Packard <keithp@keithp.com>
Daniel Vetter [Thu, 8 Sep 2011 12:00:21 +0000 (14:00 +0200)]
drm/i915: close PM interrupt masking races in the rps work func
This patch closes the following race:
We get a PM interrupt A, mask it, set dev_priv->iir = PM_A and kick of the
work item. Scheduler isn't grumpy, so the work queue takes rps_lock,
grabs pm_iir = dev_priv->pm_iir and pm_imr = READ(PMIMR). Note that
pm_imr == pm_iir because we've just masked the interrupt we've got.
Now hw sends out PM interrupt B (not masked), we process it and mask
it. Later on the irq handler also clears PMIIR.
Then the work item proceeds and at the end clears PMIMR. Because
(local) pm_imr == pm_iir we have
pm_imr & ~pm_iir == 0
so all interrupts are enabled.
Hardware is still interrupt-happy, and sends out a new PM interrupt B.
PMIMR doesn't mask B (it does not mask anything), PMIIR is cleared, so
we get it and hit the WARN in the interrupt handler (because
dev_priv->pm_iir == PM_B).
That's why I've moved the
WRITE(PMIMR, 0)
up under the protection of the rps_lock. And write an uncoditional 0
to PMIMR, because that's what we'll do anyway.
This races looks much more likely because we can arbitrarily extend
the window by grabing dev->struct mutex right after the irq handler
has processed the first PM_B interrupt.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Ben Widawsky <ben@bwidawsk.net> Signed-off-by: Keith Packard <keithp@keithp.com>
Daniel Vetter [Thu, 8 Sep 2011 12:00:20 +0000 (14:00 +0200)]
drm/i915: close PM interrupt masking races in the irq handler
Quoting Chris Wilson's more concise description:
"Ah I think I see the problem. As you point out we only mask the current
interrupt received, so that if we have a task pending (and so IMR != 0) we
actually unmask the pending interrupt and so could receive it again before the
tasklet is finally kicked off by the grumpy scheduler."
We need the hw to issue PM interrupts A, B, A while the scheduler is hating us
and refuses to run the rps work item. On receiving PM interrupt A we hit the
WARN because
dev_priv->pm_iir == PM_A | PM_B
Also add a posting read as suggested by Chris to ensure proper ordering of the
writes to PMIMR and PMIIR. Just in case somebody weakens write ordering.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Ben Widawsky <ben@bwidawsk.net> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Keith Packard <keithp@keithp.com>
Adam Jackson [Thu, 16 Jun 2011 20:36:23 +0000 (16:36 -0400)]
drm/i915: Remove "i2c_speed" nonsense from child device table
I have no evidence for this byte being used this way, and lots of
counterexamples. Restore the struct to its empirical definition and
patch up gmbus setup to match.
Signed-off-by: Adam Jackson <ajax@redhat.com> Acked-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Keith Packard <keithp@keithp.com>
Keith Packard [Mon, 19 Sep 2011 06:09:52 +0000 (23:09 -0700)]
drm/i915: Disable eDP VDD in a delayed work proc instead of synchronously
There's no good reason to turn off the eDP force VDD bit synchronously
while probing devices; that just sticks a huge delay into all mode
setting paths. Instead, queue a delayed work proc to disable the VDD
force bit and then remember when that fires to ensure that the
appropriate delay is respected before trying to turn it back on.
Keith Packard [Wed, 28 Sep 2011 23:48:10 +0000 (16:48 -0700)]
drm/i915: Correct eDP panel power sequencing delay computations
Store the panel power sequencing delays in the dp private structure,
rather than the global device structure. Who knows, maybe we'll get
more than one eDP device in the future.
From the eDP spec, we need the following numbers:
T1 + T3 Power on to Aux Channel operation (panel_power_up_delay)
This marks how long it takes the panel to boot up and
get ready to receive aux channel communications.
T8 Video signal to backlight on (backlight_on_delay)
Once a valid video signal is being sent to the device,
it can take a while before the panel is actuall
showing useful data. This delay allows the panel
to get something reasonable up before the backlight
is turned on.
T9 Backlight off to video off (backlight_off_delay)
Turning the backlight off can take a moment, so
this delay makes sure there is still valid video
data on the screen.
T10 Video off to power off (panel_power_down_delay)
Presumably this delay allows the panel to perform
an orderly shutdown of the display.
T11 + T12 Power off to power on (panel_power_cycle_delay)
So, once you turn the panel off, you have to wait a
while before you can turn it back on. This delay is
usually the longest in the entire sequence.
Neither the VBIOS source code nor the hardware documentation has a
clear mapping between the delay values they provide and those required
by the eDP spec. The VBIOS code actually uses two different labels for
the delay values in the five words of the relevant VBT table.
**** MORE LATER ***
Look at both the current hardware register settings and the VBT
specified panel power sequencing timings. Use the maximum of the two
delays, to make sure things work reliably. If there is no VBT data,
then those values will be initialized to zero, so we'll just use the
values as programmed in the hardware. Note that the BIOS just fetches
delays from the VBT table to place in the hardware registers, so we
should get the same values from both places, except for rounding.
VBT doesn't provide any values for T1 or T2, so we'll always just use
the hardware value for that.
The panel power up delay is thus T1 + T2 + T3, which should be
sufficient in all cases.
The panel power down delay is T1 + T2 + T12, using T1+T2 as a proxy
for T11, which isn't available anywhere.
For the backlight delays, the eDP spec says T6 + T8 is the delay from the
end of link training to backlight on and T9 is the delay from
backlight off until video off. The hardware provides a 'backlight on'
delay, which I'm taking to be T6 + T8 while the VBT provides something
called 'T7', which I'm assuming is s
On the macbook air I'm testing with, this yields a power-up delay of
over 200ms and a power-down delay of over 600ms. It all works now, but
we're frobbing these power controls several times during mode setting,
making the whole process take an awfully long time.
Keith Packard [Wed, 28 Sep 2011 23:44:14 +0000 (16:44 -0700)]
drm/i915: Ensure eDP powered up during DP_SET_POWER operation in dp_prepare
Any call to intel_dp_sink_dpms must ensure that the panel has power so
that the DP_SET_POWER operation will be correctly received. The only
one missing this was in intel_dp_prepare.
Signed-off-by: Keith Packard <keithp@keithp.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Keith Packard [Wed, 28 Sep 2011 23:38:44 +0000 (16:38 -0700)]
drm/i915: Wrap DP EDID fetch functions to enable eDP panel power
Talking to the eDP DDC channel requires that the panel be powered
up. Wrap both the EDID and modes fetch code with calls to turn the vdd
power on and back off.
Signed-off-by: Keith Packard <keithp@keithp.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Keith Packard [Thu, 6 Oct 2011 02:53:09 +0000 (19:53 -0700)]
drm/i915: Ensure panel is on during DPMS off
If the panel is already off, we'll need to turn VDD on to execute the
(useless) DPMS off code. Yes, it would be better to just not do any of
this, but correctness, and *then* performance.
Keith Packard [Mon, 19 Sep 2011 21:33:26 +0000 (14:33 -0700)]
drm/i915: Only use VBT panel mode on eDP if no EDID is found
We're going to assume that EDID is more reliable than the VBT tables
for eDP panels, which is notably true on MacBook machines where the
VBT contains completely bogus data.
Signed-off-by: Keith Packard <keithp@keithp.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Keith Packard [Tue, 27 Sep 2011 05:24:57 +0000 (22:24 -0700)]
drm/i915: Initialize PCH refclks at modeset init time
The reference clock configuration must be done before any mode setting
can occur as all outputs must be disabled to change
anything. Initialize the clocks after turning everything off during
the initialization process.
Keith Packard [Mon, 26 Sep 2011 21:29:12 +0000 (14:29 -0700)]
drm/i915: Use CK505 as non-SSC source where available
When trying to use SSC on Ibex Peak without CK505, any non-SSC outputs
(like VGA or TV) get broken. So, do not use SSC on Ibex Peak unless
there is a CK505 available (as specified by the VBT).
On Cougar Point, all clocking is internal, so SSC can always be used,
and there will never be a CK505 available.
This eliminates VGA shimmer on some Ironlake machines which have a
CK505 clock source.
References: https://bugzilla.kernel.org/show_bug.cgi?id=21742
References: https://bugs.freedesktop.org/show_bug.cgi?id=38750 Signed-off-by: Keith Packard <keithp@keithp.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Keith Packard [Thu, 22 Sep 2011 19:01:57 +0000 (12:01 -0700)]
drm/i915: Fix PCH SSC reference clock settings
The PCH refclk settings are global, so we need to look at all of the
encoders, not just the current encoder when deciding how to configure
it. Also, handle systems with more than one panel (any combination of
PCH/non-PCH eDP and LVDS).
Keith Packard [Mon, 26 Sep 2011 21:24:14 +0000 (14:24 -0700)]
drv/i915: Pull display_clock_mode out of VBT table
This tells the driver whether a CK505 clock source is available on
pre-PCH hardware. If so, it should be used as the non-SSC source,
leaving the internal clock for use as the SSC source.
Signed-off-by: Keith Packard <keithp@keithp.com> Reviewed-by: Chris Wison <chris@chris-wilson.co.uk>
Keith Packard [Tue, 20 Sep 2011 04:34:19 +0000 (21:34 -0700)]
drm/i915: FBC off for ironlake and older, otherwise on by default
Make the default FBC behaviour chipset specific, allowing us to turn
it on by default for Ironlake and older where it has been seen to
cause trouble with screen updates.
Signed-off-by: Keith Packard <keithp@keithp.com> Tested-by: Francis Moreau <francis.moro@gmail.com>
Simon Farnsworth [Wed, 21 Sep 2011 16:13:30 +0000 (17:13 +0100)]
drm/i915: Enable SDVO hotplug interrupts for HDMI and DVI
I was seeing a nasty 5 frame glitch every 10 seconds, caused by the
poll for connection on DVI attached by SDVO.
As my SDVO DVI supports hotplug detect interrupts, the fix is to
enable them, and hook them in to the various bits of driver
infrastructure so that they work reliably.
Note that this is only tested on single-function DVI-D SDVOs, on two
platforms (965GME and 945GSE), and has not been checked against a
specification document.
With lots of help from Adam Jackson <ajax@redhat.com> on IRC.
Signed-off-by: Simon Farnsworth <simon.farnsworth@onelan.co.uk> Reviewed-by: Keith Packard <keithp@keithp.com> Signed-off-by: Keith Packard <keithp@keithp.com>
Ben Widawsky [Thu, 15 Sep 2011 03:32:47 +0000 (20:32 -0700)]
drm/i915: Dumb down the semaphore logic
While I think the previous code is correct, it was hard to follow and
hard to debug. Since we already have a ring abstraction, might as well
use it to handle the semaphore updates and compares.
I don't expect this code to make semaphores better or worse, but you
never know...
v2:
Remove magic per Keith's suggestions.
Ran Daniel's gem_ring_sync_loop test on this.
v3:
Ignored one of Keith's suggestions.
v4:
Removed some bloat per Daniel's recommendation.
Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Keith Packard <keithp@keithp.com> Signed-off-by: Ben Widawsky <ben@bwidawsk.net> Signed-off-by: Keith Packard <keithp@keithp.com>
Add ELD support for Intel Eaglelake, IbexPeak/Ironlake,
SandyBridge/CougarPoint and IvyBridge/PantherPoint chips.
ELD (EDID-Like Data) describes to the HDMI/DP audio driver the audio
capabilities of the plugged monitor. It's built and passed to audio
driver in 2 steps:
(1) at get_modes time, parse EDID and save ELD to drm_connector.eld[]
(2) at mode_set time, write drm_connector.eld[] to the Transcoder's hw
ELD buffer and set the ELD_valid bit to inform HDMI/DP audio driver
This patch is tested OK on G45/HDMI, IbexPeak/HDMI and IvyBridge/HDMI+DP.
Test scheme: plug in the HDMI/DP monitor, and run
cat /proc/asound/card0/eld*
to check if the monitor name, HDMI/DP type, etc. show up correctly.
Minor imperfection: the GEN5_AUD_CNTL_ST/DIP_Port_Select field always
reads 0 (reserved). Without knowing the port number, I worked it around
by setting the ELD_valid bit for ALL the three ports. It's tested to not
be a problem, because the audio driver will find invalid ELD data and
hence rightfully abort, even when it sees the ELD_valid indicator.
Thanks to Zhenyu and Pierre-Louis for a lot of valuable help and testing.
CC: Zhao Yakui <yakui.zhao@intel.com> CC: Wang Zhenyu <zhenyu.z.wang@intel.com> CC: Jeremy Bush <contractfrombelow@gmail.com> CC: Christopher White <c.white@pulseforce.com> CC: Pierre-Louis Bossart <pierre-louis.bossart@intel.com> CC: Paul Menzel <paulepanter@users.sourceforge.net> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Keith Packard <keithp@keithp.com>
ELD (EDID-Like Data) describes to the HDMI/DP audio driver the audio
capabilities of the plugged monitor.
This adds drm_edid_to_eld() for converting EDID to ELD. The converted
ELD will be saved in a new drm_connector.eld[128] data field. This is
necessary because the graphics driver will need to fixup some of the
data fields (eg. HDMI/DP connection type, AV sync delay) before writing
to the hardware ELD buffer. drm_av_sync_delay() will help the graphics
drivers dynamically compute the AV sync delay for fixing-up the ELD.
ELD selection policy: it's possible for one encoder to be associated
with multiple connectors (ie. monitors), in which case the first found
ELD will be returned by drm_select_eld(). This policy may not be
suitable for all users, but let's start it simple first.
The impact of ELD selection policy: assume there are two monitors, one
supports stereo playback and the other has 8-channel output; cloned
display mode is used, so that the two monitors are associated with the
same internal encoder. If only the stereo playback capability is reported,
the user won't be able to start 8-channel playback; if the 8-channel ELD
is reported, then user space applications may send 8-channel samples
down, however the user may actually be listening to the 2-channel
monitor and not connecting speakers to the 8-channel monitor.
According to James, many TVs will either refuse the display anything or
pop-up an OSD warning whenever they receive hdmi audio which they cannot
handle. Eventually we will require configurability and/or per-monitor
audio control even when the video is cloned.
CC: Zhao Yakui <yakui.zhao@intel.com> CC: Wang Zhenyu <zhenyu.z.wang@intel.com> CC: Jeremy Bush <contractfrombelow@gmail.com> CC: Christopher White <c.white@pulseforce.com> CC: Pierre-Louis Bossart <pierre-louis.bossart@intel.com> CC: Paul Menzel <paulepanter@users.sourceforge.net> CC: James Cloos <cloos@jhcloos.com> CC: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Ben Skeggs <bskeggs@redhat.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Keith Packard <keithp@keithp.com>
We want to enable dithering on any pipe where the frame buffer has
more color resolution than the output device.
The previous code was incorrectly clamping the frame buffer bpc to the
display bpc, effectively disabling dithering all of the time as the
computed frame buffer bpc would never be larger than the display bpc.
Signed-off-by: Keith Packard <keithp@keithp.com> Reported-by: Oliver Hartkopp <socketcan@hartkopp.net> Tested-by: Oliver Hartkopp <socketcan@hartkopp.net>
Dave Airlie [Tue, 20 Sep 2011 08:35:22 +0000 (09:35 +0100)]
Merge branch 'drm-nouveau-next' of git://git.freedesktop.org/git/nouveau/linux-2.6 into drm-next
* 'drm-nouveau-next' of git://git.freedesktop.org/git/nouveau/linux-2.6: (353 commits)
drm/nouveau: remove allocations from gart populate() hook
drm/nvc0/fb: slightly improve PMFB intr handling, move out of nvc0_graph.c
drm/nvc0/fifo: avoid touching missing subfifos
drm/nvd9/disp: bail out of mode_set_base if no fb bound to crtc
drm/nvd9/disp: stub some more api hooks so we don't oops on resume
drm/nouveau: fix printk typo in ioremap failure path
drm/nvc0/pm: minor clock readback fixes
drm/nv40/pm: execute memory reset script from vbios
drm/nv50/gr: refactor initialisation
drm/nouveau: if requested, try harder at disabling sysmem pushbufs
drm/nv50/gr: enable ctxprog xfer only when we need it to save power
drm/nouveau/dp: add support for displayport table 0x30
drm/nouveau/dp: return master dp table pointer too when looking up encoder
drm/nouveau/bios: simplify U/d table hash matching func to just match
drm/nouveau/dp: preserve non-pattern bits in DP_TRAINING_PATTERN_SET
drm/nvc0/gr: remove MODULE_FIRMWARE() lines
drm/nouveau/dp: use alternate lane mask for nvaf
drm/nouveau/dp: link rate scripts are selected with a comparison table
drm/nv40/pm: write nv40-specific reclocking routines
drm/nv40/pm: parse geometric delta clock from vbios
...
Ben Skeggs [Tue, 30 Aug 2011 04:30:11 +0000 (14:30 +1000)]
drm/nouveau: remove allocations from gart populate() hook
Since some somewhat questionable changes a while back, TTM provides a
completely empty array of struct dma_address that stays around for the
entire lifetime of the TTM object.
Lets use this array, *always*, rather than wasting yet more memory on
another array who's purpose is identical, as well as yet another bool array
of the same size saying *which* of the previous two arrays to use...
This change will also solve the high order allocation failures seen by
some people while using nouveau.
Martin Peres [Sat, 30 Jul 2011 21:08:45 +0000 (23:08 +0200)]
drm/nv50/gr: enable ctxprog xfer only when we need it to save power
This patch adds instructions to ctxprog and by doing, impacts context
switching performance. My testcase showed a 1% performance cost using
glxgears that is a context-switch bound application.
Please test and report bugs/performance/power/other.
Many thanks to Maxim Levitsky for his dedicated work on lowering power
consumption with nouveau.
Not 100% perfect yet, but a good start towards what it'll look like in the
end.
Actually seems stable on a NV44 I have here, as much as running around OA
for a fair amount of time constantly switching between performance levels
can prove..
My NV49 isn't quite so happy, and semaphores mess up somehow (sometimes) as
a result of the memory reclocking.
Ben Skeggs [Mon, 18 Jul 2011 06:02:37 +0000 (16:02 +1000)]
drm/nv40/pm: parse geometric delta clock from vbios
This changes the meaning of what we reported as "core" clock previously.
The shader/rop units are allegedly supposed to be run at the base clock
listed in the perf table, while the geometric clock can be bumped from
this value on some boards.
So that we can report both, we'll report the base clock as "shader" (since
the shaders *do* run at it), and the geometric clock as "core".
Roy Spliet [Sat, 9 Jul 2011 19:18:11 +0000 (21:18 +0200)]
drm/nouveau/pm: add initial NV3x/NVCx memtiming support, improve other cards
NV30: Create framework for memtm
NV50: Improve reg creation,
NV50: Use P.version instead of card codename/stepping,
NVC0: Initial memtiming code for Fermi,
Renamed regs for consistency,
Overall redesign to improve readability,
Avoid kfree on null-pointer
Signed-off-by: Roy Spliet <r.spliet@student.tudelft.nl>