drm/vc4: module dysfunctional on Raspberry Pi 3B as of 5.18.0

[Stefan Wahren]

Hi Peter,

Am 09.06.22 um 13:52 schrieb Peter Robinson:
>>>>> As of Linux 5.18.0, module vc4 apparently isn't working on Raspberry Pi
>>>>> 3B any more.
>>>>>
>>>>> If a monitor is attached to the device, the boot messages show up as
>>>>> usual, but right when KMS starts, the screen turns black. Similarly, the
>>>>> screen also turns black when the module is blacklisted at boot time and
>>>>> loaded from the running system.
>>>>> The problem looks quite similar to the one posted some months ago in [1].
>>> If I understand you properly, it results in a blank screen if the
>>> monitor is connected, but the system is still responsive?
>>>
>>> If so, it's a very different problem than the link you provided, since
>>> it was occurring when no monitor was connected and resulted in a total
>>> system hang.
>>>
>>>>> Unfortunately, looking through systemd's journal didn't seem to yield
>>>>> any real hint. Nevertheless, the results from grepping vc4 are
>>>> I'm seeing the same issue with vc4 on a RPi3 on 5.18.1 on Fedora so
>>>> can confirm the regression. Maxime would know what might be up here?
>> i assume you are using the downstream DTB?
> In this case it's the one in the Linux kernel (not sure if that's
> upstream or downstream in this context) not the one provided by the
> RPi firmware.

okay thanks. I tried the kernel config but its huge.

Is it correct that the issue occurs with your kernel config, but not 
with multi_v7_defconfig?

>
>> Please provide the version/date of the GPU firmware?
> [    6.205121] raspberrypi-firmware soc:firmware: Attached to firmware
> from 2022-05-24T13:26:52
> Which is git f145afc
This is good. I had issues with older firmware which didn't implement 
RPI_FIRMWARE_NOTIFY_DISPLAY_DONE. So it must be something different.