Re: Interlaced resolutions hang the desktop

[Alex Deucher <alexdeucher@gmail.com>]

Does disabling pageflipping via the xorg.conf help?

Alex

On Wed, Mar 31, 2021 at 1:40 PM Christian König
<christian.koenig@amd.com> wrote:
>
> Yeah, agree that must be some kind of bug in the upper layer of the stack.
>
> Most likely some userspace component is not handling the specialties of interlacing correctly (different vblank timing every other frame).
>
> It probably only works on Intel and after restarting the display manager by coincident.
>
> Sorry, but as I said this is a use case which basically nobody is using any more and because of this the different parts of the stack are not tested well enough for this.
>
> Christian.
>
> Am 31.03.21 um 17:47 schrieb Alberto Salvia Novella:
>
> Restarting the display manager service works and, more importantly, makes the bug no longer reproducible.
>
> Restarting the window manager doesn't work.
>
> Changing display manager makes the bug still reproducible.
>
> Maybe this is due to xorg-server, isn't it?
>
> On Wed, 31 Mar 2021 at 16:55, Christian König <ckoenig.leichtzumerken@gmail.com> wrote:
>>
>> Well the hardware is working fine as far as I can see.
>>
>> Can you try to kill the X server over SSH and see if you then get some screen update?
>>
>> Regards,
>> Christian.
>>
>> Am 31.03.21 um 16:52 schrieb Alberto Salvia Novella:
>>
>> Output.
>>
>> On Wed, 31 Mar 2021 at 16:36, Christian König <christian.koenig@amd.com> wrote:
>>>
>>> Mhm strange.
>>>
>>> Can you get me the output of "sudo cat /sys/kernel/debug/dri/0/radeon_fence_info" when the problem happens?
>>>
>>> Thanks,
>>> Christian.
>>>
>>> Am 31.03.21 um 16:33 schrieb Alberto Salvia Novella:
>>>
>>> - The computer still replies to ping.
>>> - The journal shows no errors, but a few warnings.
>>> - The mouse doesn't freeze.
>>>
>>> On Wed, 31 Mar 2021 at 10:09, Christian König <christian.koenig@amd.com> wrote:
>>>>
>>>> Can you access the system over the network and see if there is anything in the system log?
>>>>
>>>> It sounds like the display stack has crashed, but when the sound keeps playing the system is most likely still responsive over network.
>>>>
>>>> Thanks,
>>>> Christian.
>>>>
>>>> Am 31.03.21 um 10:05 schrieb Alberto Salvia Novella:
>>>>
>>>> What happens is this simple: after a few minutes, about 6 or so, the entire content of the screen stays still. In some minor situations only the applications panel of KDE Plasma.
>>>>
>>>> If music is playing it continues playing, so only graphics are hung. Yet in most cases the power button won't shut down the computer, as it usually does.
>>>>
>>>> At least this is the case using kwin on x11, and not on wayland. It only happens on "radeon" and not on Intel or "radeonhd".
>>>>
>>>> On Wed, 31 Mar 2021 at 09:48, Christian König <christian.koenig@amd.com> wrote:
>>>>>
>>>>> Correct, but a TV is intended for videos only. That's why it implements only the lower HDMI standard.
>>>>>
>>>>> Interlaced transmits only halve the lines with each frame, so a 60Hz mode effectively either becomes a 30Hz mode, halving the vertical resolution or adaptive motion compensated which the know visual artifacts. Depending on what the deinterlacing setting on your TV is.
>>>>>
>>>>> You could just add a progressive 1920x540@60 or 1920x1080@30 mode manually and would have the same effect with probably better quality. See https://de.wikipedia.org/wiki/Deinterlacing for reference.
>>>>>
>>>>> If you can give us some more information what is happening when the system freeze we could try to narrow this down, but we can't spend much time on a very specific use case in a driver which is in maintenance mode.
>>>>>
>>>>> Regards,
>>>>> Christian.
>>>>>
>>>>> Am 31.03.21 um 09:21 schrieb Alberto Salvia Novella:
>>>>>
>>>>> 24fps is intended for video only. Anything interactive at 24fps, as just moving the mouse around, is extremely choppy.
>>>>>
>>>>> No way anyone would prefer that over an interlaced resolution or a lower resolution. That is, by far, the worst option.
>>>>>
>>>>> Just try it on your screen, set it to 24Hz or alike, and tell me your experience. You can't even tell where the mouse is going to go.
>>>>>
>>>>> On Wed, 31 Mar 2021 at 08:44, Christian König <christian.koenig@amd.com> wrote:
>>>>>>
>>>>>> Hi Alberto,
>>>>>>
>>>>>> well a frame rate of 24Hz is perfectly reasonable for a TV and desktop usage.
>>>>>>
>>>>>> This is probably caused by the TVs limited HDMI bandwidth and a refresh rate of 30/25 Hz for the interlaced mode isn't much better either.
>>>>>>
>>>>>> Regards,
>>>>>> Christian.
>>>>>>
>>>>>> Am 30.03.21 um 22:59 schrieb Alberto Salvia Novella:
>>>>>>
>>>>>> The frame-rate at 24Hz is extremely poor for normal desktop usage.
>>>>>>
>>>>>> If the highest resolution, aka 1080p, uses that refresh rate then the desktop will default to that frame-rate.
>>>>>>
>>>>>> Other progressive modes don't exhibit any issue.
>>>>>>
>>>>>> On Tue, 30 Mar 2021 at 18:26, Christian König <christian.koenig@amd.com> wrote:
>>>>>>>
>>>>>>> Hi Alberto,
>>>>>>>
>>>>>>> I think the driver should only support resolutions that are progressive, but also at least of 50Hz.
>>>>>>>
>>>>>>>
>>>>>>> Why do you think so?, the 24Hz resolution seems to be the native one of the display.
>>>>>>>
>>>>>>> Regards,
>>>>>>> Christian.
>>>>>>>
>>>>>>> Am 30.03.21 um 17:37 schrieb Alberto Salvia Novella:
>>>>>>>
>>>>>>> This is why I'm using interlaced:
>>>>>>>
>>>>>>> $ xrandr
>>>>>>> Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
>>>>>>> DisplayPort-0 disconnected (normal left inverted right x axis y axis)
>>>>>>> HDMI-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 16mm x 9mm
>>>>>>>    1920x1080i    60.00*+  50.00    59.94
>>>>>>>    1920x1080     24.00    23.98
>>>>>>>    1280x720      60.00    50.00    59.94
>>>>>>>    1024x768      75.03    70.07    60.00
>>>>>>>    832x624       74.55
>>>>>>>    800x600       72.19    75.00    60.32    56.25
>>>>>>>    720x576       50.00
>>>>>>>    720x576i      50.00
>>>>>>>    720x480       60.00    59.94
>>>>>>>    720x480i      60.00    59.94
>>>>>>>    640x480       75.00    72.81    66.67    60.00    59.94
>>>>>>>    720x400       70.08
>>>>>>> DVI-0 disconnected (normal left inverted right x axis y axis)
>>>>>>>
>>>>>>> I think the driver should only support resolutions that are progressive, but also at least of 50Hz.
>>>>>>>
>>>>>>> On Tue, 30 Mar 2021 at 15:41, Christian König <ckoenig.leichtzumerken@gmail.com> wrote:
>>>>>>>>
>>>>>>>> Mhm, no idea why an interlaced resolution would cause a crash. Maybe some miscalculation in the display code.
>>>>>>>>
>>>>>>>> But apart from that if you just connected your PC to a TV I also wouldn't recommend using an interlaced resolution in the first place.
>>>>>>>>
>>>>>>>> See those resolutions only exists for backward compatibility with analog hardware.
>>>>>>>>
>>>>>>>> I think we would just disable those modes instead of searching for the bug.
>>>>>>>>
>>>>>>>> Regards,
>>>>>>>> Christian.
>>>>>>>>
>>>>>>>> Am 30.03.21 um 11:07 schrieb Alberto Salvia Novella:
>>>>>>>>
>>>>>>>> I guessed so.
>>>>>>>>
>>>>>>>> The GPU is a Radeon HD5870, and the screen is an old Telefunken TV (TLFK22LEDPVR1).
>>>>>>>>
>>>>>>>> Since my real display got into repair I used this TV meanwhile, and to my surprise it froze the system.
>>>>>>>>
>>>>>>>> On Tue, 30 Mar 2021 at 10:15, Christian König <christian.koenig@amd.com> wrote:
>>>>>>>>>
>>>>>>>>> Hi Alberto,
>>>>>>>>>
>>>>>>>>> well what hardware do you have?
>>>>>>>>>
>>>>>>>>> Interlaced resolutions are not used any more on modern hardware, so they
>>>>>>>>> are not well tested.
>>>>>>>>>
>>>>>>>>> Regards,
>>>>>>>>> Christian.
>>>>>>>>>
>>>>>>>>> Am 30.03.21 um 10:04 schrieb Alberto Salvia Novella:
>>>>>>>>> > The entire desktop hangs after some minutes when using the module
>>>>>>>>> > "radeon" with an interlaced resolution.
>>>>>>>>> >
>>>>>>>>> > Easier to trigger by playing a video on Firefox, at least on kwin_x11.
>>>>>>>>> > Wayland didn't exhibit the problem.
>>>>>>>>> >
>>>>>>>>> > Other display drivers, from different computers I have tried, didn't
>>>>>>>>> > allow those interlaced resolutions all together. It seems they know
>>>>>>>>> > there will be problems.
>>>>>>>>>
>>>>>>>>
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>>>>>>>> amd-gfx@lists.freedesktop.org
>>>>>>>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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