commit 9569002a39cdc17b11f415f16215ec2428dad902
author Philippe CORNU <philippe.cornu@st.com> Thu Feb 01 11:42:43 2018 +0100
committer Benjamin Gaignard <benjamin.gaignard@linaro.org> Thu Feb 08 10:23:32 2018 +0100
tree 180aba86e6c6aa5d2204661b1951008915f5f35e
parent aefa830199c3d07e198d44f55aa781f119937854

drm/stm: ltdc: remove non-alpha color formats on layer 2 for older hw

Hw older versions support non-alpha color formats derived
from native alpha color formats only on the primary layer.
For instance, RG16 native format without alpha works fine
on 2nd layer but XR24 (derived color format from AR24)
does not work on 2nd layer.

Signed-off-by: Philippe Cornu <philippe.cornu@st.com>
Reviewed-by: Yannick Fertré <yannick.fertre@st.com>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180201104243.20726-3-philippe.cornu@st.com

drivers/gpu/drm/stm/ltdc.c

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index f6f26fc..1a3277e 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -703,6 +703,11 @@ static void ltdc_plane_atomic_update(struct drm_plane *plane,
 	if (!fb->format->has_alpha)
 		val = BF1_CA | BF2_1CA;
 
+	/* Manage hw-specific capabilities */
+	if (ldev->caps.non_alpha_only_l1 &&
+	    plane->type != DRM_PLANE_TYPE_PRIMARY)
+		val = BF1_PAXCA | BF2_1PAXCA;
+
 	reg_update_bits(ldev->regs, LTDC_L1BFCR + lofs,
 			LXBFCR_BF2 | LXBFCR_BF1, val);
 
@@ -785,6 +790,12 @@ static struct drm_plane *ltdc_plane_create(struct drm_device *ddev,
 		drm_fmt_no_alpha = get_pixelformat_without_alpha(drm_fmt);
 		if (!drm_fmt_no_alpha)
 			continue;
+
+		/* Manage hw-specific capabilities */
+		if (ldev->caps.non_alpha_only_l1 &&
+		    type != DRM_PLANE_TYPE_PRIMARY)
+			continue;
+
 		formats[nb_fmt++] = drm_fmt_no_alpha;
 	}
 
@@ -913,10 +924,19 @@ static int ltdc_get_caps(struct drm_device *ddev)
 	case HWVER_10300:
 		ldev->caps.reg_ofs = REG_OFS_NONE;
 		ldev->caps.pix_fmt_hw = ltdc_pix_fmt_a0;
+		/*
+		 * Hw older versions support non-alpha color formats derived
+		 * from native alpha color formats only on the primary layer.
+		 * For instance, RG16 native format without alpha works fine
+		 * on 2nd layer but XR24 (derived color format from AR24)
+		 * does not work on 2nd layer.
+		 */
+		ldev->caps.non_alpha_only_l1 = true;
 		break;
 	case HWVER_20101:
 		ldev->caps.reg_ofs = REG_OFS_4;
 		ldev->caps.pix_fmt_hw = ltdc_pix_fmt_a1;
+		ldev->caps.non_alpha_only_l1 = false;
 		break;
 	default:
 		return -ENODEV;