DRM/AST regression (likely 4.14 -> 4.19+), providing EDID manually fails

[Jani Nikula]

On Mon, 27 May 2019, Ashutosh Dixit <ashutosh.dixit at intel.com> wrote:
> On Sun, 26 May 2019 12:50:51 -0700, Ilpo Järvinen wrote:
>>
>> Hi all,
>>
>> I've a workstation which has internal VGA that is detected as AST 2400 and
>> with it EDID has been always quite flaky (except for some time it worked
>> with 4.14 long enough that I thought the problems would be past until the
>> problems reappeared also with 4.14). Thus, I've provided manually the EDID
>> that I extracted from the monitor using other computer (the monitor itself
>> worked just fine on the earlier computer so it is likely fine).
>>
>> I setup the manual EDID using drm_kms_helper.edid_firmware, however,
>> after upgrading to 4.19.45 it stopped working (no "Got external EDID base
>> block" appears in dmesg, the text mode is kept in the lower res mode, and
>> Xorg logs no longer dumps the EDID info like it did with 4.14). So I guess
>> the EDID I provided manually on the command line is not correctly put into
>> use with 4.19+ kernels.
>>
>> The 4.19 dmesg indicated that drm_kms_helper.edid_firmware is deprecated
>> so I also tested with drm.edid_firmware it suggested as the replacement
>> but with no luck (but I believe also the drm_kms_helper one should have
>> worked as it was only "deprecated").
>>
>> I also tried 5.1.2 but it did not work any better (and with it also tried
>> removing all the manual *.edid_firmware from the command line so I still
>> need to provide one manually to have it reliable working it seems).
>
> I believe there is a bug already tracking this, here:
>
> https://bugs.freedesktop.org/show_bug.cgi?id=107583

Ilpo, does video=VGA-1:e command-line option work around the problem for
you?

BR,
Jani.


-- 
Jani Nikula, Intel Open Source Graphics Center