[PATCH v2 3/3] drm/i915/gen9+: Add support for pipe background color (v2)

[Matt Roper]

Gen9+ platforms allow CRTC's to be programmed with a background/canvas
color below the programmable planes.  Let's expose this for use by
compositors.

v2:
 - Split out bgcolor sanitization and programming of csc/gamma bits to a
   separate patch that we can land before the ABI changes are ready to
   go in.  (Ville)
 - Change a temporary variable name to be more consistent with
   other similar functions.  (Ville)
 - Change register name to SKL_CANVAS for consistency with the
   CHV_CANVAS register.

Cc: dri-devel at lists.freedesktop.org
Cc: wei.c.li at intel.com
Cc: harish.krupo.kps at intel.com
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c  |  9 +++++++++
 drivers/gpu/drm/i915/intel_display.c | 35 ++++++++++++++++++++++++++++-------
 2 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 670db5073d70..1f2a19e6ec79 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3254,6 +3254,15 @@ static int i915_display_info(struct seq_file *m, void *unused)
 			intel_plane_info(m, crtc);
 		}
 
+		if (INTEL_GEN(dev_priv) >= 9 && pipe_config->base.active) {
+			uint64_t background = pipe_config->base.bgcolor;
+
+			seq_printf(m, "\tbackground color (10bpc): r=%x g=%x b=%x\n",
+				   DRM_RGBA_RED(background, 10),
+				   DRM_RGBA_GREEN(background, 10),
+				   DRM_RGBA_BLUE(background, 10));
+		}
+
 		seq_printf(m, "\tunderrun reporting: cpu=%s pch=%s \n",
 			   yesno(!crtc->cpu_fifo_underrun_disabled),
 			   yesno(!crtc->pch_fifo_underrun_disabled));
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 1d089d93d88b..e7a759e0c021 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3834,6 +3834,27 @@ void intel_finish_reset(struct drm_i915_private *dev_priv)
 	clear_bit(I915_RESET_MODESET, &dev_priv->gpu_error.flags);
 }
 
+static void skl_update_background_color(const struct intel_crtc_state *cstate)
+{
+	struct intel_crtc *crtc = to_intel_crtc(cstate->base.crtc);
+	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+	uint64_t propval = cstate->base.bgcolor;
+	uint32_t tmp;
+
+	/* Hardware is programmed with 10 bits of precision */
+	tmp = DRM_RGBA_RED(propval, 10) << 20
+	    | DRM_RGBA_GREEN(propval, 10) << 10
+	    | DRM_RGBA_BLUE(propval, 10);
+
+	/*
+	 * Set CSC and gamma for bottom color to ensure background pixels
+	 * receive the same color transformations as plane content.
+	 */
+	tmp |= SKL_CANVAS_CSC_ENABLE | SKL_CANVAS_GAMMA_ENABLE;
+
+	I915_WRITE_FW(SKL_CANVAS(crtc->pipe), tmp);
+}
+
 static void intel_update_pipe_config(const struct intel_crtc_state *old_crtc_state,
 				     const struct intel_crtc_state *new_crtc_state)
 {
@@ -3869,14 +3890,8 @@ static void intel_update_pipe_config(const struct intel_crtc_state *old_crtc_sta
 			ironlake_pfit_disable(old_crtc_state);
 	}
 
-	/*
-	 * We don't (yet) allow userspace to control the pipe background color,
-	 * so force it to black, but apply pipe gamma and CSC so that its
-	 * handling will match how we program our planes.
-	 */
 	if (INTEL_GEN(dev_priv) >= 9)
-		I915_WRITE(SKL_CANVAS(crtc->pipe),
-			   SKL_CANVAS_GAMMA_ENABLE | SKL_CANVAS_CSC_ENABLE);
+		skl_update_background_color(new_crtc_state);
 }
 
 static void intel_fdi_normal_train(struct intel_crtc *crtc)
@@ -10896,6 +10911,9 @@ static int intel_crtc_atomic_check(struct drm_crtc *crtc,
 		crtc_state->planes_changed = true;
 	}
 
+	if (crtc_state->bgcolor_changed)
+		pipe_config->update_pipe = true;
+
 	ret = 0;
 	if (dev_priv->display.compute_pipe_wm) {
 		ret = dev_priv->display.compute_pipe_wm(pipe_config);
@@ -14035,6 +14053,9 @@ static int intel_crtc_init(struct drm_i915_private *dev_priv, enum pipe pipe)
 
 	WARN_ON(drm_crtc_index(&intel_crtc->base) != intel_crtc->pipe);
 
+	if (INTEL_GEN(dev_priv) >= 9)
+		drm_crtc_add_bgcolor_property(&intel_crtc->base);
+
 	return 0;
 
 fail:
-- 
2.14.4