Re: [PATCH] drm: verisilicon: fix cursor offset field update

On Wed, Aug 12, 2026 at 11:48 PM Icenowy Zheng <[email protected]> wrote:
>
> The 4th argument of regmap_update_bits() expects a pre-shifted register
> value instead of the field value when it's used to set a single field,
> however I forgot this when writing the code setting the cursor X/Y
> offset fields, thus the write operation doesn't happen at all (because
> of the non-shifted values being masked by regmap_update_bits()).
>
> Fix this problem so the cursor is correctly clipped.
>
> The framebuffer address is also clipped so the cursor offset problem was
> previously not discovered, and the framebuffer address deserves another
> fix for proper cursor behavior when it's clipped.
>
> Fixes: 8c4ae2189125 ("drm: verisilicon: add support for cursor planes")
> Signed-off-by: Icenowy Zheng <[email protected]>

Make sense.

Reviewed-by: Chen-Yu Tsai <[email protected]>

> ---
>  drivers/gpu/drm/verisilicon/vs_cursor_plane.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/verisilicon/vs_cursor_plane.c b/drivers/gpu/drm/verisilicon/vs_cursor_plane.c
> index fa4f601dd0c87..4ce311ae48823 100644
> --- a/drivers/gpu/drm/verisilicon/vs_cursor_plane.c
> +++ b/drivers/gpu/drm/verisilicon/vs_cursor_plane.c
> @@ -199,7 +199,7 @@ static void vs_cursor_plane_atomic_update(struct drm_plane *plane,
>         } else {
>                 regmap_update_bits(dc->regs, VSDC_CURSOR_CONFIG(output),
>                                    VSDC_CURSOR_CONFIG_X_OFF_MASK,
> -                                  -state->crtc_x);
> +                                  VSDC_CURSOR_CONFIG_X_OFF(-state->crtc_x));
>                 regmap_update_bits(dc->regs, VSDC_CURSOR_LOCATION(output),
>                                    VSDC_CURSOR_LOCATION_X_MASK, 0);
>         }
> @@ -213,7 +213,7 @@ static void vs_cursor_plane_atomic_update(struct drm_plane *plane,
>         } else {
>                 regmap_update_bits(dc->regs, VSDC_CURSOR_CONFIG(output),
>                                    VSDC_CURSOR_CONFIG_Y_OFF_MASK,
> -                                  -state->crtc_y);
> +                                  VSDC_CURSOR_CONFIG_Y_OFF(-state->crtc_y));
>                 regmap_update_bits(dc->regs, VSDC_CURSOR_LOCATION(output),
>                                    VSDC_CURSOR_LOCATION_Y_MASK, 0);
>         }
> --
> 2.52.0
>