[PATCH] drm/gma500: Add CedarView LVDS blacklist

[Hans de Goede]

Hi,

On 16-04-19 16:32, Patrik Jakobsson wrote:
> On Wed, Apr 10, 2019 at 1:51 PM Dominik 'Rathann' Mierzejewski
> <dominik at greysector.net> wrote:
>>
>> On Wednesday, 10 April 2019 at 13:33, Patrik Jakobsson wrote:
>>> On Wed, Apr 10, 2019 at 1:18 PM Dominik 'Rathann' Mierzejewski
>>> <dominik at greysector.net> wrote:
>>>>
>>>> On Wednesday, 10 April 2019 at 11:08, Hans de Goede wrote:
>>>>> On 10-04-19 11:00, Patrik Jakobsson wrote:
>>>>>> On Wed, Apr 10, 2019 at 9:27 AM Hans de Goede <hdegoede at redhat.com> wrote:
>>>>>>> On 09-04-19 21:31, Dominik 'Rathann' Mierzejewski wrote:
>>>>>>>> On Tuesday, 09 April 2019 at 16:44, Hans de Goede wrote:
>>>>>>>>> On 09-04-19 14:05, Patrik Jakobsson wrote:
>>>> [...]
>>>>>>>>>> I'm not totally against this but not sure about the consequences. Is
>>>>>>>>>> there perhaps a better dmi string to match against?
>>>>>>>>>
>>>>>>>>> No there are no better DMI strings to match against I'm afraid.
>>>>>>>>
>>>>>>>> I did load default settings in BIOS setup and there's no change in
>>>>>>>> behaviour. LVDS gets detected as connected:
>>>>>>>> $ cat /sys/class/drm/card0-LVDS-1/status
>>>>>>>> connected
>>>>>>>>
>>>>>>>> Only VGA output is physically connected at the moment.
>>>>>>>
>>>>>>> To be clear what Dominik means here is that he has a VGA monitor
>>>>>>> connected. There is no LVDS panel in this device at all.
>>>>>>
>>>>>> Thanks for testing. I dusted off my DN2800MT and tried turning LVDS
>>>>>> on/off in the BIOS. With LVDS disabled gma500 reports it as connected.
>>>>>> When LVDS is enabled in bios I instead get a connected eDP connector.
>>>>>> I'm starting to think that broken VBT parsing might be the actual
>>>>>> problem.
>>>>>
>>>>> Maybe, but I assume there are CedarView based laptops with LVDS panels
>>>>> which works, so I suspect this might be more of a bug in your BIOS.
>>>>>
>>>>> So what is the next step in debugging this?
>>>>
>>>> To add a small twist, I got an updated BIOS from the vendor to fix
>>>> another issue (https://bugzilla.kernel.org/show_bug.cgi?id=199117)
>>>> and the DMI string has changed to: "CDV W Series 05", so Hans' patch
>>>> no longer matches my machine.
>>>
>>> Hi Dominik,
>>>
>>> Do you have any option to enable/disable LVDS in your BIOS. The BIOS
>>> default might not be to disable LVDS since they apparently solved the
>>> issue on the command line anyway. If there is an option to turn it off
>>> but you still get the same problem, then it is possible that detection
>>> of "LVDS disabled" in the driver might be bad.
>>
>> No, there's no option to enable/disable LVDS. The machine is a NAS box
>> and doesn't have an LVDS physically. You can see the motherboard e.g.
>> here: https://youtu.be/ZYNQvZNGLsE?t=855 .
> 
> I've posted a patch: https://patchwork.freedesktop.org/patch/299821/
> 
> Previously we only checked for a child device and ignored the lvds
> config bits. Hopefully this fixes your problem.

Dominik,

As also discussed in bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=1665766#c23

I've started a Fedora kernel test-build with Patrik's patch added,
please test this:
https://koji.fedoraproject.org/koji/taskinfo?taskID=34215831

Regards,

Hans