drm/i915/pfit: Check pfit destination window on ILK-BDW

The ILK-BDW panel fitter has several restrictions on the
destination window size. Check for those and reject the
configuration if things aren't entirely proper.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241016143134.26903-7-ville.syrjala@linux.intel.com
Acked-by: Jani Nikula <jani.nikula@intel.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
index 593e41907d53..d66ce8537f7d 100644
--- a/drivers/gpu/drm/i915/display/intel_panel.c
+++ b/drivers/gpu/drm/i915/display/intel_panel.c
@@ -383,6 +383,57 @@ void intel_panel_add_encoder_fixed_mode(struct intel_connector *connector,
 				   "current (BIOS)");
 }
 
+static int intel_pch_pfit_check_dst_window(const struct intel_crtc_state *crtc_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;
+	const struct drm_rect *dst = &crtc_state->pch_pfit.dst;
+	int width = drm_rect_width(dst);
+	int height = drm_rect_height(dst);
+	int x = dst->x1;
+	int y = dst->y1;
+
+	if (adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE &&
+	    (y & 1 || height & 1)) {
+		drm_dbg_kms(display->drm,
+			    "[CRTC:%d:%s] pfit window (" DRM_RECT_FMT ") misaligned for interlaced output\n",
+			    crtc->base.base.id, crtc->base.name, DRM_RECT_ARG(dst));
+		return -EINVAL;
+	}
+
+	/*
+	 * "Restriction : When pipe scaling is enabled, the scaled
+	 *  output must equal the pipe active area, so Pipe active
+	 *  size = (2 * PF window position) + PF window size."
+	 *
+	 * The vertical direction seems more forgiving than the
+	 * horizontal direction, but still has some issues so
+	 * let's follow the same hard rule for both.
+	 */
+	if (adjusted_mode->crtc_hdisplay != 2 * x + width ||
+	    adjusted_mode->crtc_vdisplay != 2 * y + height) {
+		drm_dbg_kms(display->drm,
+			    "[CRTC:%d:%s] pfit window (" DRM_RECT_FMT ") not centered\n",
+			    crtc->base.base.id, crtc->base.name, DRM_RECT_ARG(dst));
+		return -EINVAL;
+	}
+
+	/*
+	 * "Restriction : The X position must not be programmed
+	 *  to be 1 (28:16=0 0000 0000 0001b)."
+	 */
+	if (x == 1) {
+		drm_dbg_kms(display->drm,
+			    "[CRTC:%d:%s] pfit window (" DRM_RECT_FMT ") badly positioned\n",
+			    crtc->base.base.id, crtc->base.name, DRM_RECT_ARG(dst));
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int intel_pch_pfit_check_src_size(const struct intel_crtc_state *crtc_state)
 {
 	struct intel_display *display = to_intel_display(crtc_state);
@@ -575,6 +626,10 @@ static int pch_panel_fitting(struct intel_crtc_state *crtc_state,
 	if (DISPLAY_VER(display) >= 9)
 		return 0;
 
+	ret = intel_pch_pfit_check_dst_window(crtc_state);
+	if (ret)
+		return ret;
+
 	ret = intel_pch_pfit_check_src_size(crtc_state);
 	if (ret)
 		return ret;