Re: [PATCH] drm/loongson: stop to set get_vblank_timestamp for 7A1000 CRTC

[Huacai Chen]

Hi, Icenowy,

On Mon, Mar 16, 2026 at 3:53 PM Thomas Zimmermann <tzimmermann@xxxxxxx> wrote:
>
>
>
> Am 14.03.26 um 17:54 schrieb Icenowy Zheng:
> > As there's no known hardware capability about querying vblank on the
> > 7A1000 display controller, setting get_vblank_timestamp will mislead the
> > kernel about the support of DC-backed high precision vblank query.
> >
> > Drop this function pointer in the CRTC function table for 7A1000.
> >
> > This solves a kernel warning when booting Linux 7.0-rc3 on a
> > 3A4000+7A1000 Haier Boyue G51 laptop (with injected EDID for replicating
Please s/3A4000/Loongson-3A4000/g and s/7A1000/LS7A1000/g, thanks.

Huacai

> > the display timing set by the firmware).
> >
> > Signed-off-by: Icenowy Zheng <zhengxingda@xxxxxxxxxxx>
>
> Acked-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
>
> > ---
> >   drivers/gpu/drm/loongson/lsdc_crtc.c | 1 -
> >   1 file changed, 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/loongson/lsdc_crtc.c b/drivers/gpu/drm/loongson/lsdc_crtc.c
> > index 587fbe285e9ef..b3af8e0cdb15f 100644
> > --- a/drivers/gpu/drm/loongson/lsdc_crtc.c
> > +++ b/drivers/gpu/drm/loongson/lsdc_crtc.c
> > @@ -721,7 +721,6 @@ static const struct drm_crtc_funcs ls7a1000_crtc_funcs = {
> >       .late_register = lsdc_crtc_late_register,
> >       .enable_vblank = lsdc_crtc_enable_vblank,
> >       .disable_vblank = lsdc_crtc_disable_vblank,
> > -     .get_vblank_timestamp = drm_crtc_vblank_helper_get_vblank_timestamp,
> >       .atomic_print_state = lsdc_crtc_atomic_print_state,
> >   };
> >
>
> --
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
> GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)
>
>