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

[Nicolas Dufresne <nicolas@ndufresne.ca>]

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Le mardi 03 février 2026 à 16:53 +0800, Ming Qian(OSS) a écrit :
> Hi Marco,
> 
> On 2/3/2026 4:31 PM, Marco Felsch wrote:
> > [You don't often get email from m.felsch@pengutronix.de. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> > 
> > Hi,
> > 
> > sorry for jumping in.
> > 
> > On 26-02-03, Ming Qian(OSS) wrote:
> > > Hi Nicolas,
> > > 
> > > On 2/3/2026 3:12 AM, Nicolas Dufresne wrote:
> > > > 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
> > > 
> > > My test results for fluster differ from yours.
> > > On my end, the results for JCT-VC-HEVC_V1 are consistent at both 300MHz and
> > > 600MHz.
> > > And results remained unchanged after multiple tests.

After more testing, the fluster test is stable for NV12/NV15 tiled output for me
too. I'm running the tests with linear NV12/P010, which imply an extra set of
buffer. I will check if I can give you a easy way to test the linear formats. I
also have couple of streams that systematically breaks at specific spot (high
complexity scenes) with the provided patch. As most licensed content, this is
not sharable as-is. I will try and see if I can find a way to share something.

> > > 
> > > I'm not sure what caused the differences between us.
> > 
> > Once it comes to system stability, you need to ensure that your
> > bootstack is aligned e.g. same TF-A version and sometimes same
> > bootloader since there might be workarounds/erratum applied by the boot
> > firmware.
> > 
> > Regards,
> >    Marco
> > 
> 
> Thanks for the reminder, and I agree.
> I think we need to align our board environment first.

I do likely have slightly different bootchain, and of course all the HDMI
component are downstream, but I can't really isolate the dramatic issue of this
overclock without a display component of some sort. Its a huge differentiator in
the bandwidth consumption which is the main challenge on this SoC so far. 10bit
videos makes things a lot worse fwiw.

We did review latest IMX vendor firmware package and can confirm we are running
the latest memory training blob and HDMI firmware.

Nicolas

> Regards,
> Ming
> 
> > > 
> > > Below are my test results:
> > > 
> > > 600Mhz, 0.9v
> > >        cat /sys/kernel/debug/regulator/regulator_summary  |grep SW1C
> > >         SW1C                             0    1      0 unknown   900mV     0mA
> > > 825mV  1100mV
> > >        cat /sys/kernel/debug/clk/vpu_g2/clk_rate
> > >        600000000
> > > 
> > >        ./fluster.py run -ts JCT-VC-HEVC_V1 -d GStreamer-H.265-V4L2SL-Gst1.0 -j2 -t
> > > 90
> > >        ****************************************************************************************************
> > >        Running test suite JCT-VC-HEVC_V1 with decoder
> > > GStreamer-H.265-V4L2SL-Gst1.0
> > >        Using 2 parallel job(s)
> > >        ****************************************************************************************************
> > > 
> > >        Ran 139/147 tests successfully               in 505.434 secs
> > >        Ran 139/147 tests successfully               in 505.350 secs
> > >        Ran 139/147 tests successfully               in 507.540 secs
> > > 
> > > 600Mhz, 1.0v
> > >        cat /sys/kernel/debug/regulator/regulator_summary  |grep SW1C
> > >         SW1C                             0    1      0 unknown  1000mV     0mA
> > > 825mV  1100mV
> > >        cat /sys/kernel/debug/clk/vpu_g2/clk_rate
> > >        600000000
> > > 
> > >        ./fluster.py run -ts JCT-VC-HEVC_V1 -d GStreamer-H.265-V4L2SL-Gst1.0 -j2 -t
> > > 90
> > >        Ran 139/147 tests successfully               in 506.901 secs
> > > 
> > > 300Mhz, 0.9v
> > >        cat /sys/kernel/debug/regulator/regulator_summary  |grep SW1C
> > >         SW1C                             0    1      0 unknown   900mV     0mA
> > > 825mV  1100mV
> > >        cat /sys/kernel/debug/clk/vpu_g2/clk_rate
> > >        300000000
> > > 
> > >        ./fluster.py run -ts JCT-VC-HEVC_V1 -d GStreamer-H.265-V4L2SL-Gst1.0 -j2 -t
> > > 90
> > >        Ran 139/147 tests successfully               in 506.063 secs
> > > 
> > > Downstream v4l2 driver
> > >        cat /sys/kernel/debug/regulator/regulator_summary  |grep SW1C
> > >         SW1C                             0    2      0 unknown  1000mV     0mA
> > > 825mV  1100mV
> > >        cat /sys/kernel/debug/clk/vpu_g2/clk_rate
> > >        600000000
> > > 
> > >        ./fluster.py run -ts JCT-VC-HEVC_V1 -d GStreamer-H.265-V4L2-Gst1.0 -j2 -t
> > > 90
> > >        Ran 136/147 tests successfully               in 460.435 secs
> > > 
> > > Regards,
> > > Ming
> > > 
> > > 
> > 
> > --
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> > #CallMeByMyFirstName
> > 
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