Regression with mainline kernel on rpi4

[Linus Torvalds]

On Wed, Sep 22, 2021 at 1:19 PM Sudip Mukherjee
<sudipm.mukherjee at gmail.com> wrote:
>
> I added some debugs to print the addresses, and I am getting:
> [   38.813809] sudip crtc 0000000000000000
>
> This is from struct drm_crtc *crtc = connector->state->crtc;

Yeah, that was my personal suspicion, because while the line number
implied "crtc->state" being NULL, the drm data structure documentation
and other drivers both imply that "crtc" was the more likely one.

I suspect a simple

        if (!crtc)
                return;

in vc4_hdmi_set_n_cts() is at least part of the fix for this all, but
I didn't check if there is possibly something else that needs to be
done too.

                Linus