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

[Ming Qian(OSS)]

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.

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