[Intel-gfx] [PATCH] drm/i915: be more careful when returning -ENXIO in gmbus transfer

[Daniel Vetter]

On Mon, May 21, 2012 at 11:31:20AM -0700, Daniel Kurtz wrote:
> On Mon, May 21, 2012 at 11:24 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > On Mon, 21 May 2012 20:19:48 +0200, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> >> ... flaky ddc hardware can cause a spurious NAK, resulting in the i2c
> >> core and drm edid functions not trying to retry the edid transfer.
> >>
> >> Luckily the gmbus quiescenting also times out for these cases, so we
> >> can get out of this mess by returning -ETIMEDOUT for this specific
> >> case. This way we keep the fast-fail of returning -ENXIO if there is
> >> no device present, speeding up the boot process.
> >>
> >> This regression has been introduced in
> >>
> >> commit e646d5773572bf52017983d758bdf05777dc5600
> >> Author: Daniel Kurtz <djkurtz at chromium.org>
> >> Date:   Fri Mar 30 19:46:38 2012 +0800
> >>
> >>     drm/i915/intel_i2c: always wait for IDLE before clearing NAK
> >>
> >> v2: Return -ETIMEDOUT for this case and keep the -ENXIO for real NAKs,
> >> suggested by Daniel Kurtz.
> >>
> >> Cc: Daniel Kurtz <djkurtz at chromium.org>
> >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49518
> >> Reported-and-Tested-by: Julian Simioni <julian.simioni at gmail.com>
> >> Signed-Off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> >
> > Acked-by: Chris Wilson <chris at chris-wilson.co.uk>
> > -Chris
> >
> > --
> > Chris Wilson, Intel Open Source Technology Centre
> 
> Reviewed-by: Daniel Kurtz <djkurtz at chromium.org>
Picked up for -fixes, thanks for the review.
-Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
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