[v2,1/2] drm/msm/dpu1: don't choke on disabling the writeback connector

[Johan Hovold]

On Fri, Aug 30, 2024 at 07:36:32PM +0200, György Kurucz wrote:

> For context, I have a Lenovo Yoga Slim 7x laptop, and was having issues 
> with the display staying black after sleep. As a workaround, I could 
> switch to a different VT and back.
> 
> > [ 1185.831970] [dpu error]connector not connected 3
> 
> I can confirm that I was seeing this exact error message as well.
> 
> >   	if (!conn_state || !conn_state->connector) {
> >   		DPU_ERROR("invalid connector state\n");
> >   		return -EINVAL;
> > -	} else if (conn_state->connector->status != connector_status_connected) {
> > -		DPU_ERROR("connector not connected %d\n", conn_state->connector->status);
> > -		return -EINVAL;
> >   	}
> >   
> >   	crtc = conn_state->crtc;
> 
> After applying this patch, the screen now resumes successfully, and the 
> errors are gone.

I'm seeing the same issue as György on the x1e80100 CRD and Lenovo
ThinkPad T14s. Without this patch, the internal display fails to resume
properly (switching VT brings it back) and the following errors are
logged:

	[dpu error]connector not connected 3
	[drm:drm_mode_config_helper_resume [drm_kms_helper]] *ERROR* Failed to resume (-22)

I see the same symptoms with Xorg as well as sway.

Can we please get this fixed and backported as soon as possible?

Even if there are further issues with some "Night Light" functionality
on one machine, keeping this bug as workaround does not seem warranted
given that it breaks basic functionality for users.

The x1e80100 is the only platform I have access to with a writeback
connector, but this regression potentially affects a whole host of older
platforms as well.

Johan