[Intel-gfx] [v2] igt/pm_rpm: Use libc 'ftw' rather than opencoding our own filetree walk

[Tahvanainen, Jari]

On Wed, Aug 23, 2017 at 05:06:42PM +0100, Chris Wilson wrote:
> By using ftw, we avoid the issue of having to handle directory recursion
> ourselves and can focus on the test of checking the reading a
> sysfs/debugfs does not break runtime suspend. In the process, disregard
> errors when opening the individual files as they may fail for other
> reasons.
> 
> v2: Bracket the file open/close with the wait_for_suspended() tests.
> Whilst the fd is open, it may be keeping the device awake, e.g.
> i915_forcewake_user.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  lib/igt_debugfs.c | 50 +++++++++++++++++++++---------
>  lib/igt_debugfs.h |  1 +
>  lib/igt_sysfs.c   | 41 +++++++++++++++++++------
>  lib/igt_sysfs.h   |  1 +
>  tests/pm_rpm.c    | 91 ++++++++++++++++++++++++-------------------------------
>  5 files changed, 108 insertions(+), 76 deletions(-)
> 

Tested-by: Jari Tahvanainen <jari.tahvanainen at intel.com>
On SKL (i5-6600k) improvement is visible in both sysfs-read and debugfs-read tests.
On 1000 repetitions both resulted to change from FAIL to SUCCESS for 1000 times on
 drm-tip: 2017y-08m-30d-08h-12m-34s UTC integration manifest
with igt commit 1f0f2aa014 + this series.
For HSW see https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_90/shards.html
Test pm_rpm:
        Subgroup debugfs-read:
                fail       -> PASS       (shard-hsw) fdo#100717
        Subgroup sysfs-read:
                fail       -> PASS       (shard-hsw) fdo#102242