[Nouveau] 640x480 does not fill screen

[Dan Espen]

Ilia Mirkin <imirkin at alum.mit.edu> writes:

> On Sat, Feb 16, 2019 at 12:49 PM Dan Espen <dan1espen at gmail.com> wrote:
>>
>> Dan Espen <dan1espen at gmail.com> writes:
>>
>> > Ilia Mirkin <imirkin at alum.mit.edu> writes:
>> >
>> >> On Wed, Feb 6, 2019 at 3:28 PM Dan Espen <dan1espen at gmail.com> wrote:
>> >>>
>> >>> Ilia Mirkin <imirkin at alum.mit.edu> writes:
>> >>>
>> >>> > It would be useful to know how the screen is connected. Also please
>> >>> > grab the monitor's EDID from /sys/class/drm/cardN-connector/edid and
>> >>> > attach it here. It would also be interesting to get a boot with
>> >>> > "drm.debug=0x1e nouveau.debug=disp=trace" which has the modeswitch in
>> >>> > question.
>> >>>
>> >>> The screen is connected using the MDP port.
>> >>> I don't find any cardN-connector directory,
>> >>> the closest match is:
>> >>>
>> >>> /sys/class/drm/card0-DP-1/edid
>> >>
>> >> N = 0
>> >> connector = DP-1
>> >>
>> >> so looks like you found it.
>> >>
>> >> I was actually looking for dmesg with those boot parameters, not the Xorg log.
>> >>
>> >> Something to randomly try -- xrandr -s 640x480 -r 75 -- perhaps it'll
>> >> like that mode better.
>> >
>> > Using "-r 75" fixes the problem.
>> >
>> >> Also does 720x480 work better?
>> >
>> > Yes, 720x480 works without the -r parameter.
>> >
>> >> Looking at your EDID, you have:
>> >>
>> >> Established timings supported:
>> >>   720x400 at 70Hz 9:5 HorFreq: 31469 Hz Clock: 28.320 MHz
>> >>   640x480 at 60Hz 4:3 HorFreq: 31469 Hz Clock: 25.175 MHz
>> >>   640x480 at 75Hz 4:3 HorFreq: 37500 Hz Clock: 31.500 MHz
>> >>   800x600 at 60Hz 4:3 HorFreq: 37900 Hz Clock: 40.000 MHz
>> >>   800x600 at 75Hz 4:3 HorFreq: 46900 Hz Clock: 49.500 MHz
>> >>   1024x768 at 60Hz 4:3 HorFreq: 48400 Hz Clock: 65.000 MHz
>> >>   1024x768 at 75Hz 4:3 HorFreq: 60000 Hz Clock: 78.750 MHz
>> >>   1280x1024 at 75Hz 5:4 HorFreq: 80000 Hz Clock: 135.000 MHz
>> >> Standard timings supported:
>> >>   1920x1080 at 60Hz 16:9
>> >>   1600x1200 at 60Hz 4:3 HorFreq: 75000 Hz Clock: 162.000 MHz
>> >>   1280x1024 at 60Hz 5:4 HorFreq: 64000 Hz Clock: 108.000 MHz
>> >>   1280x800 at 60Hz 16:10
>> >>   1152x864 at 75Hz 4:3 HorFreq: 67500 Hz Clock: 108.000 MHz
>> >>
>> >> CTA extension block
>> >> Extension version: 3
>> >> 25 bytes of CTA data
>> >>   Video data block
>> >> ...
>> >>     VIC   3 720x480 at 60Hz 16:9  HorFreq: 31469 Hz Clock: 27.000 MHz
>> >>     VIC   2 720x480 at 60Hz 4:3  HorFreq: 31469 Hz Clock: 27.000 MHz
>> >>     VIC   1 640x480 at 60Hz 4:3  HorFreq: 31469 Hz Clock: 25.175 MHz
>> >
>> > Okay, if I read all that right the EDID supports 640x480 at 60 and 75hz.
>> > The monitor acts strangely at 60hz but is okay at 75hz.
>> > Is this something I should configure or can nouveau figure out the best mode?
>>
>> Okay, looks like I'm moving back to the Nvidia proprietary drivers until
>> at least this issue is fixed.
>>
>> So, I'd like to file a bug report but I tried here:
>>
>> https://bugs.freedesktop.org/enter_bug.cgi
>>
>> and my mailing list userid/password don't work there.
>>
>> So, could someone give me guidance on filing the bug report or file one
>> on my behalf?
>>
>> It looks like the issue is, when switching modes, if there are multiple
>> matches on the resolution, Nouveau should pick the mode with the
>> highest frequency.
>
> I don't know if that's the right policy. Either way, nouveau is not
> responsible for things like that ... it just does what it's told. Why
> doesn't the 60hz mode work?

I don't know why 60hz doesn't work.
It displays text but doesn't fill the screen vertically.

I don't know for sure that nouveau is to blame, but I do know
that the NVIDIA drivers on the same hardware do the right thing.

> Is NVIDIA's driver able to drive the monitor at 640x480 at 60? If so, we
> should figure out what the difference is.

As far as I can tell, NVIDIA is driving the monitor at 640x480 at 75.
I'm working on getting the NVIDIA driver working again, I'll see
if I can find the frequency when I'm done.

Mainly what I see is that Nouveau gives me an unusable 640x480,
NVIDIA gives me a workable 640x480.

> As for filing bugs, bugzilla is separate from mailman.

Okay, got a bug report filed.

-- 
Dan Espen