Re: [PATCH drm-misc-next] rockchip/drm: vop2: don't check color_mgmt_changed in atomic_enable

["Diederik de Haas" <didi.debian@cknow.org>]

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Hi Andy,

On Sun Jun 8, 2025 at 2:10 PM CEST, Andy Yan wrote:
> At 2025-06-08 19:08:50, "Diederik de Haas" <didi.debian@cknow.org> wrote:
>>On Sat Jun 7, 2025 at 5:32 PM CEST, Piotr Zalewski wrote:
>>> On Thursday, June 5th, 2025 at 10:13 PM, Diederik de Haas <didi.debian@cknow.org> wrote:
>>>> Since kernel 6.14-rc1 I have the problem that visual output is no longer
>>>> shown on my PineTab2 and a `git bisect` pointed to this patch/commit
>>>> as the culprit. What is important to note is that `CONFIG_DRM=m` seems
>>>> to be required as the problem does not occur with `CONFIG_DRM=y`.
>>>> 
>>>> Near the end of my bisect session, something interesting occurred.
>>>> I was booted into a 'bad' kernel (ie no visual output) and when I
>>>> started to build my final kernel, I closed the lid of the PineTab2 which
>>>> made it go into suspend. When my final kernel was built, I opened the
>>>> lid again, which made it resume, to transfer my final kernel to it.
>>>> And much to my surprise, I then did have visual output.
>>>> When I read the (below) commit message of the 'offending' commit, it may
>>>> not be such a surprise after all.
>>>> 
>>>> I did try it on a Quartz64-B (also rk3566) and it did not have any issue
>>>> (output via HDMI).
>>>> I don't know what the cause for this issue is, hopefully you do.
>>>
>>> I tested and confirmed that this happens with drm=m but also in my case 
>>> it happened when drm=y. After some testing I found out that at boot modeset
>>
>>Interesting that it also happened with drm=y.
>>As you're more knowledgeable then I am with this, maybe look through
>>https://lists.sr.ht/~diederik/pine64-discuss/<D9AM2OOLREO0.2JMAI42J06TW0@cknow.org>
>>
>>to see if you may spot something relevant?
>>
>>> happened twice and at short interval and since this patch allows for gamma 
>>> LUT update regardless of color_mgmt_changed state this makes DSP CTRL GAMMA 
>>> LUT EN bit to be unset twice too. It seems that VOP does not like it. I 
>>
>>Happy to see you found the cause :-)
>>Do you happen to know why it was unset twice? That sounds suboptimal.
>>But (IIUC) setting a bit to a value it already has causing issues,
>>sounds surprising as well.
>
> I have conducted tests on both rk3566-box-demo (with drm set to y) and rk3568-lubancat-2 (with drm set to m), 
> but I was unable to reproduce this issue. Could you two please share your kernel defconfig and the corresponding kernel startup logs? 
> Additionally, both of my two boards tested with HDMI output. What kind of display interface does your board use for output?

I wasn't able to reproduce this issue on my PINE64 Quartz-B (rk3566) 
with HDMI output either, but the problem is present on a PineTab2 [1]
(also rk3566) which uses a MIPI DSI connection to the display panel.

Kernel config:
https://paste.sr.ht/~diederik/aa747ed170aa01cc759fbe1ffd9cebe8c887b10b

dmesg kernel 6.14-rc1:
https://paste.sr.ht/~diederik/733fbf8bb7f6aee8b68cf5a652157d445462c24a

dmesg kernel 6.14-rc1 with Piotr's patch:
https://paste.sr.ht/~diederik/db1af672cfb611acbfbdf35adb6f170e5c38febc

Both dmesg outputs contain a suspend-resume cycle.
I'm using a USB Wi-Fi adapter for the wireless connection.

[1] https://wiki.pine64.org/wiki/PineTab2

Happy to provide more info and/or do some tests.

Cheers,
  Diederik

>>> patched vop2_vp_dsp_lut_disable function so that dsp_ctrl is set only if 
>>> GAMMA LUT EN bit is set. I checked that this also does not break the gamma 
>>> lut functionality with emphasis on out-of/into suspend behavior.
>>>
>>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
>>> index d0f5fea15e21..7ddf311b38c6 100644
>>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
>>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
>>> @@ -897,6 +897,9 @@ static void vop2_vp_dsp_lut_disable(struct vop2_video_port *vp)
>>>  {
>>>  	u32 dsp_ctrl = vop2_vp_read(vp, RK3568_VP_DSP_CTRL);
>>>  
>>> +	if ((dsp_ctrl & RK3568_VP_DSP_CTRL__DSP_LUT_EN) == 0)
>>> +		return;
>>> +
>>>  	dsp_ctrl &= ~RK3568_VP_DSP_CTRL__DSP_LUT_EN;
>>>  	vop2_vp_write(vp, RK3568_VP_DSP_CTRL, dsp_ctrl);
>>>  }
>>
>>I built a kernel with 6.14-rc1 + this patch and can confirm the screen
>>has output again :-)
>>
>>> I will wait with sending a patch because maybe Andy has something to add 
>>> to this.
>>
>>Sounds like a plan. It could be that this issue surfaced an underlaying
>>issue and if so, fixing that would be even better.

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