[drm:vc4_hvs_irq_handler [vc4]] *ERROR* HVS underrun

[Stefan Wahren]

Am 26.10.24 um 15:11 schrieb Stefan Wahren:
> Hi,
> during the investigations of the recent VC4 HDMI Sink issue [1], I was
> able to reproduce another issue with vc4 after s2idle resume.
> Sometimes ( probability ~ 1 : 30 cases ) I'm able to trigger a HVS
> underrun and it's impact is that the HDMI display stays black and
> unusable:
>
> [ 1790.139465] PM: suspend exit
> [ 1790.153998] lan78xx 1-1.1.1:1.0 eth0: Link is Down
> [ 1790.548866] vc4-drm soc:gpu: [drm:vc4_hvs_irq_handler [vc4]]
> *ERROR* HVS underrun
> [ 1794.713952] net_ratelimit: 2 callbacks suppressed
>
> So I need to use the Debug UART after that.
gentle ping ...
>
> Scenario:
>
> Steps:
> 1. Flash latest Raspberry Pi OS (32 bit) on SD card
> 2. Build Kernel from repo [2] which based on Linux 6.12-rc3 above with
> arm/multi_v7_defconfig
> 3. Replace Kernel, modules + DTB on SD card with build ones
> 4. add the following to confix.txt
> device_tree=bcm2837-rpi-3-b-plus.dtb
> enable_uart=1
> 5. change/add the following to cmdline.txt
> console=ttyS1,11520 no_console_suspend=1
> 6. connect the following devices to Raspberry Pi 3 B+ :
> USB mouse
> USB keyboard
> Logilink HDMI switch + HDMI monitor
> Debug UART adapter (USB side to PC)
> 7. Power on board and boot into X11
> 8. Change to root
> 9. Enable wakeup for ttyS1 ( echo enabled >
> /sys/class/tty/ttyS1/power/wakeup )
> 10. Trigger suspend to idle via X11 (echo freeze > /sys/power/state)
> 11. Wakeup Raspberry Pi via Debug UART Currently I don't see a
> relation to the VC4 HDMI Sink issue, because this issue occur
> independently. Until now i wasn't able to reproduce it without the
> HDMI Switch. Not sure this is related but sometimes the cursor is also
> corrupted with noise after resume. What can I do to investigate this
> further?
> [1] -
> https://lore.kernel.org/dri-devel/c657d3e9-e4fb-4dac-a611-45655511e500@gmx.net/
> [2] - https://github.com/lategoodbye/linux-dev/commits/v6.12-pm_v2/
>
>