vc4: HDMI Sink doesn't support RGB, something's wrong.

[Maxime Ripard]

On Thu, Oct 17, 2024 at 05:26:46PM GMT, Stefan Wahren wrote:
> Am 17.10.24 um 16:27 schrieb Maxime Ripard:
> > On Wed, Oct 16, 2024 at 07:16:43PM GMT, Dave Stevenson wrote:
> > > Hi Stefan
> > > 
> > > On Tue, 15 Oct 2024 at 22:13, Stefan Wahren <wahrenst at gmx.net> wrote:
> > > > Hi Dave,
> ...
> > > > i prepared a branch for you, which contains the latest suspend2idle patches:
> > > > 
> > > > https://github.com/lategoodbye/linux-dev/commits/v6.12-pm/
> > > > 
> > > > Steps:
> > > > 1. Flash latest Raspberry Pi OS (32 bit) on SD card
> > > > 2. Build Kernel from repo 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=ttyS1,115200
> > > > no_console_suspend=1
> > > > 6. connect the following devices to Raspberry Pi 3 B+ :
> > > > USB mouse
> > > > USB keyboard
> > > > 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
> > > So I remember for next time
> > > 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
> > > I don't get the error you are seeing, but I also don't get the display resuming.
> > > pm has obviously killed the power to the HDMI block, and it has the
> > > reset values in as can be seen via /sys/kernel/debug/dri/0/hdmi_regs.
> > > Nothing in the driver restores these registers, and I'm not sure if it
> > > is meant to do so.
> > > Run kmstest or similar from this state and the change of mode
> > > reprogrammes the blocks so we get the display back again.
> > > 
> > > I've also enabled CONFIG_DRM_LOAD_EDID_FIRMWARE so that I can use your
> > > EDID, and get the same results.
> > > 
> > > Knee-capping the HDMI block on suspend seems an unlikely mechanism to
> > > work reliably. On the more recent Pis there is a need to be quite
> > > careful in disabling the pipeline to avoid getting data stuck in
> > > FIFOs.
> > > I feel I must be missing something here.
> >
> > I think we're probably missing calls to drm_mode_config_helper_suspend and
> > drm_mode_config_helper_resume.
>
> Okay, i tried this and it works better (HDMI resumes fast), but it also
> triggers a lot of WARN

vc4_plane_reset deviates from the helper there:
https://elixir.bootlin.com/linux/v6.11.3/source/drivers/gpu/drm/drm_atomic_state_helper.c#L326

We should adjust it.

> and the "doesn't support RGB ..." warnings are still there.
> 
> I pushed my changes to the branch and attached the dmesg output.

I can't help you there, it doesn't make sense to me. The EDID should be correct.

Maxime
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