[PATCH] drm: Reduce EDID warnings from DRM_ERROR to DRM_NOTE

[Sean Paul]

On Mon, Feb 13, 2017 at 3:59 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> On Mon, Feb 13, 2017 at 08:41:10AM +0100, Thierry Reding wrote:
>> On Fri, Feb 10, 2017 at 07:59:13PM +0000, Chris Wilson wrote:
>> > The warnings from parsing the EDID are not driver errors, but the
>> > "normal but significant" conditions from the external device. As such,
>> > they do not need the ferocity of an *ERROR*, but can use the less harsh
>> > DRM_NOTE instead.
>> >
>> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>> > ---
>> >  drivers/gpu/drm/drm_edid.c | 15 ++++++++-------
>> >  1 file changed, 8 insertions(+), 7 deletions(-)
>>
>> The below are all conditions that happen when the EDID is bad. I'm not
>> sure that really qualifies as "normal".
>
> Often it is - a bad EDID on the monitor will always be bad. The
> challenge is distinguishing that from silent data corruption during the
> read - a reported read failure are trivial.
>
>> From a quick look through the code we don't always trigger an error from
>> the below failure paths at higher levels, so decreasing the level here
>> has the potential to let this kind of exceptional condition go
>> unnoticed.
>
> The messages are not gone, they are higher than the default loglevel,
> but now below the level at which they are printed to a terminal. The
> bad EDID is either expected or recoverable, and definitely not fatal
> so I don't think an *ERROR* is justified.

I tend to agree.

The description for the KERN_NOTICE level is "normal but significant
condition". I might argue that the presence of these EDID messages
represents a normal *or* significant condition (depending on why the
EDID is bad), but I don't think it's unreasonable to expect people to
check their logs if the display/mode is not working properly.

Sean



> -Chris
>
> --
> Chris Wilson, Intel Open Source Technology Centre
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-- 
Sean Paul, Software Engineer, Google / Chromium OS