linux/drivers/gpu
Daniel Vetter 9cca306880 drm/i915: Handle inaccurate time conversion issues
So apparently jiffies<->nsec<->ktime isn't accurate or something. At
elast if we timeout there's occasionally still a few hundred us left
(in a 2 second timeout).

Stuff I've tried and thrown out again:
- Sampling the before timestamp before jiffies. Doesn't improve test
  path rate at all.
- Using jiffies. Way to inaccurate, which means way too much drift
  with signals plus automatic ioctl restarting in userspace. In
  hindsight we should have used an absolute timeout, but hey we need
  something for v3 of the i915 gem wait interfaces ;-)
- Trying to figure out where accuracy gets lost. gl testcase really
  don't care all that much about this (as long as isn't not massively
  off), it's just that the testcase gets a bit upset if it receives an
  EITME with timeout > 0.

So as long as we're in the ballbark it's good enough. So patch
everything up if we're at most one jiffies off. I get's me a solid
test again.

This regression is probably introduced in

commit 5ed0bdf21a
Author: Thomas Gleixner <tglx@linutronix.de>
Date:   Wed Jul 16 21:05:06 2014 +0000

    drm: i915: Use nsec based interfaces

    Use ktime_get_raw_ns() and get rid of the back and forth timespec
    conversions.

    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
    Signed-off-by: John Stultz <john.stultz@linaro.org>

Probably because I'm too lazy to confirm myself and still waiting for
QA ;-)

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=82749
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
2014-12-05 15:24:45 +02:00
..
drm drm/i915: Handle inaccurate time conversion issues 2014-12-05 15:24:45 +02:00
host1x gpu: host1x: mipi: Set MIPI_CAL_BIAS_PAD_CFG1 register 2014-11-13 16:11:57 +01:00
ipu-v3 IPUv3 fixes for v3.18 2014-10-07 14:31:14 +10:00
vga Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 16:23:15 +02:00
Makefile gpu: ipu-v3: Move i.MX IPUv3 core driver out of staging 2014-06-04 11:06:52 +02:00