linux-kernel - [PATCH v2 4/7] drm/connector: hdmi: Use YUV420 output format as an RGB fallback

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250311-hdmi-conn-yuv-v2-4-fbdb94f02562@collabora.com>
Date: Tue, 11 Mar 2025 12:57:36 +0200
From: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Dave Stevenson <dave.stevenson@...pberrypi.com>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: kernel@...labora.com, dri-devel@...ts.freedesktop.org, 
 linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/7] drm/connector: hdmi: Use YUV420 output format as an
 RGB fallback

Try to make use of YUV420 when computing the best output format and
RGB cannot be supported for any of the available color depths.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
---
 drivers/gpu/drm/display/drm_hdmi_state_helper.c | 69 +++++++++++++------------
 1 file changed, 35 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
index a70e204a8df3ac1c2d7318e81cde87a83267dd21..f2052781b797dd09b41127e33d98fe25408a9b23 100644
--- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
+++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
@@ -287,8 +287,9 @@ hdmi_try_format_bpc(const struct drm_connector *connector,
 	struct drm_device *dev = connector->dev;
 	int ret;
 
-	drm_dbg_kms(dev, "Trying %s output format\n",
-		    drm_hdmi_connector_get_output_format_name(fmt));
+	drm_dbg_kms(dev, "Trying %s output format with %u bpc\n",
+		    drm_hdmi_connector_get_output_format_name(fmt),
+		    bpc);
 
 	if (!sink_supports_format_bpc(connector, info, mode, fmt, bpc)) {
 		drm_dbg_kms(dev, "%s output format not supported with %u bpc\n",
@@ -313,47 +314,22 @@ hdmi_try_format_bpc(const struct drm_connector *connector,
 }
 
 static int
-hdmi_compute_format(const struct drm_connector *connector,
-		    struct drm_connector_state *conn_state,
-		    const struct drm_display_mode *mode,
-		    unsigned int bpc)
-{
-	struct drm_device *dev = connector->dev;
-
-	/*
-	 * TODO: Add support for YCbCr420 output for HDMI 2.0 capable
-	 * devices, for modes that only support YCbCr420.
-	 */
-	if (hdmi_try_format_bpc(connector, conn_state, mode, bpc, HDMI_COLORSPACE_RGB)) {
-		conn_state->hdmi.output_format = HDMI_COLORSPACE_RGB;
-		return 0;
-	}
-
-	drm_dbg_kms(dev, "Failed. No Format Supported for that bpc count.\n");
-
-	return -EINVAL;
-}
-
-static int
-hdmi_compute_config(const struct drm_connector *connector,
-		    struct drm_connector_state *conn_state,
-		    const struct drm_display_mode *mode)
+hdmi_try_format(const struct drm_connector *connector,
+		struct drm_connector_state *conn_state,
+		const struct drm_display_mode *mode,
+		unsigned int max_bpc, enum hdmi_colorspace fmt)
 {
 	struct drm_device *dev = connector->dev;
-	unsigned int max_bpc = clamp_t(unsigned int,
-				       conn_state->max_bpc,
-				       8, connector->max_bpc);
 	unsigned int bpc;
 	int ret;
 
 	for (bpc = max_bpc; bpc >= 8; bpc -= 2) {
-		drm_dbg_kms(dev, "Trying with a %d bpc output\n", bpc);
-
-		ret = hdmi_compute_format(connector, conn_state, mode, bpc);
-		if (ret)
+		ret = hdmi_try_format_bpc(connector, conn_state, mode, bpc, fmt);
+		if (!ret)
 			continue;
 
 		conn_state->hdmi.output_bpc = bpc;
+		conn_state->hdmi.output_format = fmt;
 
 		drm_dbg_kms(dev,
 			    "Mode %ux%u @ %uHz: Found configuration: bpc: %u, fmt: %s, clock: %llu\n",
@@ -368,6 +344,31 @@ hdmi_compute_config(const struct drm_connector *connector,
 	return -EINVAL;
 }
 
+static int
+hdmi_compute_config(const struct drm_connector *connector,
+		    struct drm_connector_state *conn_state,
+		    const struct drm_display_mode *mode)
+{
+	unsigned int max_bpc = clamp_t(unsigned int,
+				       conn_state->max_bpc,
+				       8, connector->max_bpc);
+	int ret;
+
+	ret = hdmi_try_format(connector, conn_state, mode, max_bpc,
+			      HDMI_COLORSPACE_RGB);
+	if (!ret)
+		return 0;
+
+	if (connector->ycbcr_420_allowed)
+		ret = hdmi_try_format(connector, conn_state, mode, max_bpc,
+				      HDMI_COLORSPACE_YUV420);
+	else
+		drm_dbg_kms(connector->dev,
+			    "%s output format not allowed for connector\n",
+			    drm_hdmi_connector_get_output_format_name(HDMI_COLORSPACE_YUV420));
+	return ret;
+}
+
 static int hdmi_generate_avi_infoframe(const struct drm_connector *connector,
 				       struct drm_connector_state *conn_state)
 {

-- 
2.48.1