[PATCH 22/41] drm/amd/display: Unify force_yuv debugfs into force_yuv_pixel_format

[<Roman.Li@amd.com>]

From: Ivan Lipski <ivan.lipski@amd.com>

[Why]
The connector exposed a single force_yuv420_output boolean debugfs and
carried force_yuv420_output / force_yuv422_output boolean fields to force a
chroma encoding. This cannot express "force RGB" or "force YCbCr444", and
diverges from the upstream amdgpu_dm which uses a single
force_yuv_pixel_format field keyed on enum dc_pixel_encoding.

[How]
- Replace the two boolean fields with a single uint8_t
  force_yuv_pixel_format holding an enum dc_pixel_encoding value
  (PIXEL_ENCODING_UNDEFINED == no override).
- Replace the force_yuv420_output boolean debugfs with a read/write
  force_yuv_pixel_format file that takes the encoding directly
  (1=RGB, 2=YCbCr422, 3=YCbCr444, 4=YCbCr420), validated against
  PIXEL_ENCODING_COUNT.
- Convert the existing readers/writers in amdgpu_dm_connector.c to the
  new field, preserving current behaviour.
- Add YCbCr444 force support now that the field can express it.

Assisted-by: Copilot:claude-opus-4.8
Reviewed-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Ivan Lipski <ivan.lipski@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  2 -
 .../display/amdgpu_dm/amdgpu_dm_connector.c   | 23 +++++---
 .../amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 57 +++++++------------
 3 files changed, 34 insertions(+), 48 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
index 1ddf5bc88a03..3524931451c8 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
@@ -857,8 +857,6 @@ struct amdgpu_dm_connector {
 	struct mutex hpd_lock;
 
 	bool fake_enable;
-	bool force_yuv420_output;
-	bool force_yuv422_output;
 	uint8_t force_yuv_pixel_format;
 	struct dsc_preferred_settings dsc_settings;
 	struct psr_caps psr_caps;
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
index 825c3408763c..4304520d2484 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
@@ -147,7 +147,7 @@ STATIC_IFN_KUNIT int dm_encoder_helper_atomic_check(struct drm_encoder *encoder,
 		int max_bpc = conn_state->max_requested_bpc;
 
 		is_y420 = drm_mode_is_420_also(&connector->display_info, adjusted_mode) &&
-			  aconnector->force_yuv420_output;
+			  aconnector->force_yuv_pixel_format == PIXEL_ENCODING_YCBCR420;
 		color_depth = amdgpu_dm_convert_color_depth_from_display_info(connector,
 								    is_y420,
 								    max_bpc);
@@ -2280,20 +2280,25 @@ amdgpu_dm_create_validate_stream_for_sink(struct drm_connector *connector,
 	 *  - RGB is the mandatory baseline and always available.
 	 *  - YCbCr444 is only meaningful for native HDMI sinks.
 	 *  - A 420-only mode collapses the mask to YCbCr420 alone.
-	 *  - The debugfs force_yuv420_output / force_yuv422_output overrides
-	 *    pin the encoding to a single value when set. An explicit YCbCr420
-	 *    force is honoured even on modes the sink only lists as RGB/4:4:4
-	 *    capable (drm_mode_is_420_also() clear), as required for HDMI
-	 *    compliance testing; dc_validate_stream() still rejects anything
-	 *    the link genuinely cannot carry. The YCbCr422 force stays gated on
+	 *  - The debugfs force_yuv_pixel_format override pins the encoding to a
+	 *    single dc_pixel_encoding when set (PIXEL_ENCODING_UNDEFINED means
+	 *    "no override"). An explicit YCbCr420 force is honoured even on
+	 *    modes the sink only lists as RGB/4:4:4 capable
+	 *    (drm_mode_is_420_also() clear), as required for HDMI compliance
+	 *    testing; dc_validate_stream() still rejects anything the link
+	 *    genuinely cannot carry. The YCbCr422/YCbCr444 forces stay gated on
 	 *    the sink's advertised caps.
 	 */
 	if (drm_mode_is_420_only(info, drm_mode) ||
-	    aconnector->force_yuv420_output) {
+	    aconnector->force_yuv_pixel_format == PIXEL_ENCODING_YCBCR420) {
 		encoding_mask = BIT(PIXEL_ENCODING_YCBCR420);
-	} else if (aconnector->force_yuv422_output &&
+	} else if (aconnector->force_yuv_pixel_format == PIXEL_ENCODING_YCBCR422 &&
 		   (info->color_formats & BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422))) {
 		encoding_mask = BIT(PIXEL_ENCODING_YCBCR422);
+	} else if (aconnector->force_yuv_pixel_format == PIXEL_ENCODING_YCBCR444 &&
+		   (info->color_formats & BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444)) &&
+		   is_hdmi_ep) {
+		encoding_mask = BIT(PIXEL_ENCODING_YCBCR444);
 	} else {
 		encoding_mask = BIT(PIXEL_ENCODING_RGB);
 
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
index 830cf8da06b4..c4b2fc690fd7 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
@@ -3199,57 +3199,42 @@ static const struct {
 };
 
 /*
- * Force YUV420 output if available from the given mode
+ * Force a specific pixel encoding for the given connector, overriding the
+ * encoding that stream validation would otherwise pick. The value is an
+ * enum dc_pixel_encoding:
+ *
+ *   0 - PIXEL_ENCODING_UNDEFINED (no override, default)
+ *   1 - PIXEL_ENCODING_RGB
+ *   2 - PIXEL_ENCODING_YCBCR422
+ *   3 - PIXEL_ENCODING_YCBCR444
+ *   4 - PIXEL_ENCODING_YCBCR420
  */
-static int force_yuv420_output_set(void *data, u64 val)
+static int force_yuv_pixel_format_set(void *data, u64 val)
 {
 	struct amdgpu_dm_connector *connector = data;
 
-	connector->force_yuv420_output = (bool)val;
-	connector->force_yuv_pixel_format = PIXEL_ENCODING_YCBCR420;
+	if (val >= PIXEL_ENCODING_COUNT)
+		return -EINVAL;
+
+	connector->force_yuv_pixel_format = (uint8_t)val;
 
 	return 0;
 }
 
 /*
- * Check if YUV420 is forced when available from the given mode
+ * Read back the pixel encoding currently forced on the given connector.
  */
-static int force_yuv420_output_get(void *data, u64 *val)
+static int force_yuv_pixel_format_get(void *data, u64 *val)
 {
 	struct amdgpu_dm_connector *connector = data;
 
-	*val = connector->force_yuv420_output;
+	*val = connector->force_yuv_pixel_format;
 
 	return 0;
 }
 
-DEFINE_DEBUGFS_ATTRIBUTE(force_yuv420_output_fops, force_yuv420_output_get,
-			 force_yuv420_output_set, "%llu\n");
-
-static int force_yuv422_output_set(void *data, u64 val)
-{
-      struct amdgpu_dm_connector *connector = data;
-
-      connector->force_yuv422_output = (bool)val;
-      connector->force_yuv_pixel_format = PIXEL_ENCODING_YCBCR422;
-
-      return 0;
-}
-
-DEFINE_DEBUGFS_ATTRIBUTE(force_yuv422_output_fops, NULL,
-                       force_yuv422_output_set, "%llu\n");
-
-static int force_yuv444_output_set(void *data, u64 val)
-{
-      struct amdgpu_dm_connector *connector = data;
-
-      connector->force_yuv_pixel_format = PIXEL_ENCODING_YCBCR444;
-
-      return 0;
-}
-
-DEFINE_DEBUGFS_ATTRIBUTE(force_yuv444_output_fops, NULL,
-                       force_yuv444_output_set, "%llu\n");
+DEFINE_DEBUGFS_ATTRIBUTE(force_yuv_pixel_format_fops, force_yuv_pixel_format_get,
+			 force_yuv_pixel_format_set, "%llu\n");
 
 /*
  *  Read Replay state
@@ -3699,9 +3684,7 @@ static const struct {
 	char *name;
 	const struct file_operations *fops;
 } connector_debugfs_entries[] = {
-		{"force_yuv420_output", &force_yuv420_output_fops},
-		{"force_yuv422_output", &force_yuv422_output_fops},
-		{"force_yuv444_output", &force_yuv444_output_fops},
+		{"force_yuv_pixel_format", &force_yuv_pixel_format_fops},
 		{"trigger_hotplug", &trigger_hotplug_debugfs_fops},
 		{"internal_display", &internal_display_fops},
 		{"odm_combine_segments", &odm_combine_segments_fops}
-- 
2.34.1