Re: [PATCH v2] drm: shmobile: Fix blank screen after resume when LCDC is stopped

[Geert Uytterhoeven]

On Fri, 13 Mar 2026 at 09:37, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> On Fri, 27 Feb 2026 at 10:57, <phucduc.bui@xxxxxxxxx> wrote:
> > > What do you mean by "deep sleep"? s2ram? In upstream, s2ram behaves
> > > the same as s2idle, and the LCD works fine after resume from s2ram on
> > > my Amadillo, with and without your patch,
> >
> > > What am I missing?
> > > Thanks!
> >
> > Thank you for your feedback.
> >
> > To clarify the "deep sleep" context, I have tested both s2idle and deep
> > states using:
> > - echo freeze > /sys/power/state
> > - echo mem > /sys/power/state
>
> OK, same for me.
>
> > On my hardware, the issue is consistently reproducible in both cases,
> > resulting in a completely white screen after resume.
>
> TL;DR it depends on kernel config.
> With my .config, your patch is not needed (but it doesn't hurt).
> With your .config, your patch is needed.
> Unfortunately I haven't found yet which config options causes this.
> I will send you my .config by personal email.
>
> Your change looks valid to me, so
> Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

And of course:
Tested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds