[Intel-gfx] [PATCH] drm: Only warn about an invalid EDID block prior to rejection

[Daniel Vetter]

On Mon, Mar 09, 2015 at 05:29:44PM +0200, Ville Syrjälä wrote:
> On Mon, Mar 09, 2015 at 11:44:05AM +0000, Chris Wilson wrote:
> > On a noisy link, we may retry the EDID reads multiple times per block
> > and still succeed. In such cases, we don't want to flood the kernel logs
> > with *ERROR* messages as we then succeed. Refactor the EDID dumping and
> > push it into the caller rather than the validator so we can suppress the
> > warnings from transient failures. In the process, we want to refactor
> > drm_load_edid_firmware() to use the common drm_do_get_edid() to share
> > the same logic (since it already duplicates it).
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > References: https://bugs.freedesktop.org/show_bug.cgi?id=89454
> 
> Could we get it to dump the number of retries it had to make to get a
> valid EDID? The retries could be due to driver bugs so we may want to
> know that they in fact occured. Otherwise we might end up with eg.
> large delays during resume without any indication what caused them.

Just aside I'm hacking around on latencytop stuff so that edid reads show
up as latency sources. Often they're done as cpu spinning (so don't show
up at all). And if not there's huge issues with piles of retries (like
here) or just very short sleeps (gmbus can only transfer 4 bytes a time).
But that would just augment whatever other debug information we dump into
dmesg.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch