[PATCH] arm64: dts: imx8mq: Restore VPU G2 clock to 600MHz for 4K60fps decoding

[Nicolas Dufresne]

Hi,

Le lundi 02 février 2026 à 13:44 -0500, Nicolas Dufresne a écrit :
> > This doesn't sound like just a VPU issue; it's related to the display or 
> > DDR.
> > If not displayed, do the fluster test cases yield different results at 
> > 600MHz and 300MHz?
> 
> Didn't you run these tests before sending ? I can try again, but in my
> internal
> notes, I wrote:
> 
>   > Tested that, and everything becomes unstable
> 
> That was before I figure-out the IRQ handler didn't handle exception bits that
> didn't stop the decoder (or dry IRQ, which strangely is common from the G2).

Ran some fluster tests now. With this patch the results is not consistent
anymore. Then I ran it with weston being started, and in the middle of the test
the display turned black. Matches my past observation. We did reproduce this on
BSP kernel too. When the display goes black, the recent hantro drivers reports:

[  827.581586] hantro-vpu 38310000.video-codec: frame decode timed out.
[  827.720201] hantro-vpu 38310000.video-codec: not all macroblocks were
decoded.


I have local patches to reduce the cascade of errors, so it likely survived
longer then last time. I will send these patches soon. The "not all macroblocks
were decoded." is triggered by a bit in the status register that is not
documented in NXP TRM. I found that bit in some VC8000D documentation (the
sucessor of G2). I concluded it was the same meaning after looking at the failed
buffer visually, it is indeed missing couple of macroblocks near th end. Each
time we see this error, the DCSS gives up and turn either black, or sometimes
other color. The second case has been tracked to a DCSS Scaler underrun, the
first we don't know.

Fluster command ran (two threads, never completes):

./fluster.py run -d GStreamer-H.265-V4L2SL-Gst1.0 -ts JCT-VC-HEVC_V1 -j2 -t90

Nicolas
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