Re: [PATCH] drm/i915/pfit: Prevent negative coordinates in center mode

Ville Syrjälä
2026-04-01T20:40:48Z

On Tue, Mar 31, 2026 at 11:46:56PM +0530, Nemesa Garg wrote:
> When the pipe_src width or height are greater than adjusted_mode hdisplay
> and vdisplay, computed x and y offsets for center mode can be negative.
> Writing negative values into the pch_fit registers result in a state error.
> Add a check to clamp these values so that they are never negative.
>
> v2: Compare in terms of pipe_src width and height.[Ville]
>
> Signed-off-by: Nemesa Garg <nemesa.garg@intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_pfit.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_pfit.c b/drivers/gpu/drm/i915/display/intel_pfit.c
> index 6dda496190e0..0edd29eef6ad 100644
> --- a/drivers/gpu/drm/i915/display/intel_pfit.c
> +++ b/drivers/gpu/drm/i915/display/intel_pfit.c
> @@ -186,6 +186,7 @@ static int pch_panel_fitting(struct intel_crtc_state *crtc_state,
> const struct drm_connector_state *conn_state)
> {
> struct intel_display *display = to_intel_display(crtc_state);
> + struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> const struct drm_display_mode *adjusted_mode =
> &crtc_state->hw.adjusted_mode;
> int pipe_src_w = drm_rect_width(&crtc_state->pipe_src);
> @@ -200,6 +201,16 @@ static int pch_panel_fitting(struct intel_crtc_state *crtc_state,
>
> switch (conn_state->scaling_mode) {
> case DRM_MODE_SCALE_CENTER:
> + if (adjusted_mode->crtc_hdisplay < pipe_src_w ||
> + adjusted_mode->crtc_vdisplay < pipe_src_h) {
> + drm_dbg_kms(display->drm,
> + "[CRTC:%d:%s] pfit center mode source (%dx%d) exceeds display (%dx%d)\n",
> + crtc->base.base.id, crtc->base.name,
> + width, height,

These should should be pipe_src_* as well.

> + adjusted_mode->crtc_hdisplay,
> + adjusted_mode->crtc_vdisplay);
> + return -EINVAL;
> + }
> width = pipe_src_w;
> height = pipe_src_h;
> x = (adjusted_mode->crtc_hdisplay - width + 1)/2;
> --
> 2.25.1

--
Ville Syrjälä
Intel