[fedora-arm] Re: Raspberry Pi 4B+ testing

On 10/24/24 3:17 AM, Peter Robinson via arm wrote:
> On Wed, 23 Oct 2024 at 21:19, Brandon Nielsen via arm
> <arm@lists.fedoraproject.org> wrote:
>>
>> On 10/23/24 2:39 PM, Troy Dawson via arm wrote:
>>> On Wed, Oct 23, 2024 at 12:16 PM Brandon Nielsen via arm
>>> <arm@lists.fedoraproject.org <mailto:arm@lists.fedoraproject.org>> wrote:
>>>
>>> Hi all,
>>>
>>> I just noticed on my Pi 4B+ that display output on the second micro
>>> HDMI
>>> port (the one further from the USB-C power supply port) is corrupted.
>>> The first port is fine.
>>>
>>> The corruption is visible as rainbow halos around text during boot, and
>>> increasingly large areas of corruption after booting to a graphical
>>> desktop (green dots, color shifts, etc.).
>>>
>>> I can confirm this with the Fedora 41 1.3 RCs for both KDE and
>>> Workstation.
>>>
>>> Has anyone else seen this? I'm trying to rule out it just being a
>>> hardware fault with my unit.
>>>
>>> Brandon Nielsen
>>>
>>>
>>> I can confirm that, and thank you very much.
>>> I had pulled an old monitor off a shelf to test and thought I was having
>>> monitor problems.
>>> I read your email, switched display ports on my rpi4b, and now it's working.
>>>
>>> Troy Dawson
>>>
>>>
>>
>> Oddly, I cannot make this happen consistently. My last 2 boots have been
>> fine on either port. When things are "fine", I can also move the cable
>> between ports with no issues.
>>
>> So far the only thing I have noticed is:
>>
>> "fedora kernel: vc4-drm gpu: swiotlb buffer is full (sz: 1146880 bytes),
>> total 32768 (slots), used 938 (slots)"
>>
>> (and similar) appearing intermittently in the logs when the monitor is
>> misbehaving.
>
> Can you try bumping up the CMA reserved memory? In the
> /boot/efi/config.txt file change the rpi4 "dtoverlay=cma,cma-256" line
> to 384 or 512 and reboot. Check it's changed with 'dmesg | grep CMA"

I will if I ever manage to reproduce the issue repeatably. I haven't
been able to make it happen again today.
--
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