Re: [PATCH 1/3] drm/dp: make aux retries less chatty

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 19 Mar 2014, Alex Deucher <alexdeucher@gmail.com> wrote:
> On Tue, Mar 18, 2014 at 3:44 AM, Jani Nikula
> <jani.nikula@linux.intel.com> wrote:
>> On Tue, 18 Mar 2014, Alex Deucher <alexdeucher@gmail.com> wrote:
>>> Switch to debug only to avoid flooding the logs.
>>> This mirrors the behavior in some other drivers.
>>
>> I'd rather think we should find out why the DP devices are replying with
>> repeated native or i2c-over-aux defers. This doesn't help; I'm not in
>> favour.
>
> While I agree with you in theory, in practice this will generate a ton
> of regression bug reports since there will be new error messages in
> the kernel log on some systems even though the displays are working
> fine.  I'm only seeing this on certain cards, others are perfectly
> fine even with the same monitors and I don't have the bandwidth right
> now to debug this further.  In all cases the monitors are working
> correctly.

I'd argue we *want* the regression reports even when everything seems to
be working fine. Otherwise we'll never fix the stuff up.

Just a while back we used to have an infinite retry loop there in i915,
until a buggy dock firmware actually deferred indefinitely. Clearly most
devices out there eventually replied with something other than
defer. We'd like to find out whether and how much the retry and/or delay
should be increased to not hit the error condition at all.

That's how I feel anyway. I'd like to see others chime in as well, and I
won't insist if y'all think the error message must go.


BR,
Jani.



-- 
Jani Nikula, Intel Open Source Technology Center