drm/omap: Implement CTM property for CRTC using OVL managers CPR matrix

Implement CTM color management property for OMAP CRTC using DSS
overlay manager's Color Phase Rotation matrix. The CPR matrix does not
exactly match the CTM property documentation. On DSS the CPR matrix is
applied after gamma table look up. However, it seems stupid to add a
custom property just for that.
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201103080310.164453-4-tomi.valkeinen@ti.com

drivers/gpu/drm/omapdrm/omap_crtc.c

@@ -391,6 +391,33 @@ static void omap_crtc_manual_display_update(struct work_struct *data)
 	}
 }
 
+static s16 omap_crtc_s31_32_to_s2_8(s64 coef)
+{
+	u64 sign_bit = 1ULL << 63;
+	u64 cbits = (u64)coef;
+
+	s16 ret = clamp_val(((cbits & ~sign_bit) >> 24), 0, 0x1ff);
+
+	if (cbits & sign_bit)
+		ret = -ret;
+
+	return ret;
+}
+
+static void omap_crtc_cpr_coefs_from_ctm(const struct drm_color_ctm *ctm,
+					 struct omap_dss_cpr_coefs *cpr)
+{
+	cpr->rr = omap_crtc_s31_32_to_s2_8(ctm->matrix[0]);
+	cpr->rg = omap_crtc_s31_32_to_s2_8(ctm->matrix[1]);
+	cpr->rb = omap_crtc_s31_32_to_s2_8(ctm->matrix[2]);
+	cpr->gr = omap_crtc_s31_32_to_s2_8(ctm->matrix[3]);
+	cpr->gg = omap_crtc_s31_32_to_s2_8(ctm->matrix[4]);
+	cpr->gb = omap_crtc_s31_32_to_s2_8(ctm->matrix[5]);
+	cpr->br = omap_crtc_s31_32_to_s2_8(ctm->matrix[6]);
+	cpr->bg = omap_crtc_s31_32_to_s2_8(ctm->matrix[7]);
+	cpr->bb = omap_crtc_s31_32_to_s2_8(ctm->matrix[8]);
+}
+
 static void omap_crtc_write_crtc_properties(struct drm_crtc *crtc)
 {
 	struct omap_drm_private *priv = crtc->dev->dev_private;
@@ -402,7 +429,15 @@ static void omap_crtc_write_crtc_properties(struct drm_crtc *crtc)
 	info.default_color = 0x000000;
 	info.trans_enabled = false;
 	info.partial_alpha_enabled = false;
-	info.cpr_enable = false;
+
+	if (crtc->state->ctm) {
+		struct drm_color_ctm *ctm = crtc->state->ctm->data;
+
+		info.cpr_enable = true;
+		omap_crtc_cpr_coefs_from_ctm(ctm, &info.cpr_coefs);
+	} else {
+		info.cpr_enable = false;
+	}
 
 	priv->dispc_ops->mgr_setup(priv->dispc, omap_crtc->channel, &info);
 }
@@ -841,7 +876,7 @@ struct drm_crtc *omap_crtc_init(struct drm_device *dev,
 	if (priv->dispc_ops->mgr_gamma_size(priv->dispc, channel)) {
 		unsigned int gamma_lut_size = 256;
 
-		drm_crtc_enable_color_mgmt(crtc, gamma_lut_size, false, 0);
+		drm_crtc_enable_color_mgmt(crtc, gamma_lut_size, true, 0);
 		drm_mode_crtc_set_gamma_size(crtc, gamma_lut_size);
 	}