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

[Marco Felsch]

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.
> 
> 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

> 
> 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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