Re: [PATCH 06/11] drm: create hdmi output property

"Sharma, Shashank" <shashank.sharma@xxxxxxxxx> · Wed, 19 Apr 2017 21:20:42 +0530

Hello Jose,

Sorry for delay in response, I was on vacation.
Please find my comments inline.

Regards
Shashank
On 4/12/2017 3:28 PM, Jose Abreu wrote:
Hi Shashank,


On 07-04-2017 17:39, Shashank Sharma wrote:
HDMI displays can support various output types, based on
the color space and subsampling type. The possible
outputs from a HDMI 2.0 monitor could be:
  - RGB
  - YCBCR 444
  - YCBCR 422
  - YCBCR 420

This patch adds a drm property, using which, a userspace
can specify its preference, for the HDMI output type.
The output type enums are similar to the mentioned outputs
above. To handle various subsampling of YCBCR output types,
this property allows two special cases:
  - DRM_HDMI_OUTPUT_YCBCR_HQ
This indicates preferred output should be YCBCR output, with highest
subsampling rate by the source/sink, which can be typically:
  - ycbcr444
  - ycbcr422
  - ycbcr420
  - DRM_HDMI_OUTPUT_YCBCR_LQ
This indicates preferred output should be YCBCR output, with lowest
subsampling rate supported by source/sink, which can be:
  - ycbcr420
  - ycbcr422
  - ycbcr444

Default value of the property is set to 0 = RGB, so no changes if you
dont set the property.
The HQ/LQ properties are a nice idea
Courtesy Ville :)
but where are you parsing
them (because in patch 07/11 you reject these properties)? Also,
you need to make sure that source and sink supports the color space.
Yes, and that's why its handling is kept in the core driver. If you see 
my I915 patches, I have parsed and handled the HQ and LQ properties in
intel_hdmi_compute_ycbcr_config function. I am rejecting the HQ/LQ in 
07/11, coz by the time we want to set AVI_IF the driver should have picked
the highest/lowest YCBCR mode, and now we should have a definite one out 
of 444,422 or 420.

Do you think it would be a good idea to find the HQ/LQ YCBCR output in 
DRM layer ? In that case it would be difficult if source supports these 
outputs

- Shashank
Best regards,
Jose Miguel Abreu

Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Jose Abreu <joabreu@xxxxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxxxx>
---
  drivers/gpu/drm/drm_atomic.c        |  2 ++
  drivers/gpu/drm/drm_atomic_helper.c |  4 ++++
  drivers/gpu/drm/drm_connector.c     | 31 +++++++++++++++++++++++++++++++
  include/drm/drm_connector.h         | 14 ++++++++++++++
  include/drm/drm_mode_config.h       |  5 +++++
  5 files changed, 56 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index f32506a..6ef34dc 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -1123,6 +1123,8 @@ int drm_atomic_connector_set_property(struct drm_connector *connector,
  		 */
  		if (state->link_status != DRM_LINK_STATUS_GOOD)
  			state->link_status = val;
+	} else if (property == config->hdmi_output_property) {
+		state->hdmi_output = val;
  	} else if (connector->funcs->atomic_set_property) {
  		return connector->funcs->atomic_set_property(connector,
  				state, property, val);
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 8be9719..fcba3c0 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -567,6 +567,10 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
  			if (old_connector_state->link_status !=
  			    new_connector_state->link_status)
  				new_crtc_state->connectors_changed = true;
+
+			if (old_connector_state->hdmi_output !=
+			    new_connector_state->hdmi_output)
+				new_crtc_state->connectors_changed = true;
  		}
  
  		if (funcs->atomic_check)
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 9f84761..10201b1 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -227,6 +227,11 @@ int drm_connector_init(struct drm_device *dev,
  					      config->edid_property,
  					      0);
  
+	if (connector_type != DRM_MODE_CONNECTOR_VIRTUAL)
+		drm_object_attach_property(&connector->base,
+					   config->hdmi_output_property,
+					   0);
+
  	drm_object_attach_property(&connector->base,
  				      config->dpms_property, 0);
  
@@ -617,6 +622,25 @@ static const struct drm_prop_enum_list drm_link_status_enum_list[] = {
  };
  DRM_ENUM_NAME_FN(drm_get_link_status_name, drm_link_status_enum_list)
  
+static const struct drm_prop_enum_list drm_hdmi_output_enum_list[] = {
+	{ DRM_HDMI_OUTPUT_DEFAULT_RGB, "output_rgb" },
+	{ DRM_HDMI_OUTPUT_YCBCR422, "output_ycbcr422" },
+	{ DRM_HDMI_OUTPUT_YCBCR444, "output_ycbcr444" },
+	{ DRM_HDMI_OUTPUT_YCBCR420, "output_ycbcr420" },
+	{ DRM_HDMI_OUTPUT_YCBCR_HQ, "output_ycbcr_high_subsampling" },
+	{ DRM_HDMI_OUTPUT_YCBCR_LQ, "output_ycbcr_low_subsampling" },
+};
+
+/**
+ * drm_get_hdmi_output_name - return a string for a given hdmi output enum
+ * @type: enum of output type
+ */
+const char *drm_get_hdmi_output_name(enum drm_hdmi_output_type type)
+{
+	return drm_hdmi_output_enum_list[type].name;
+}
+EXPORT_SYMBOL(drm_get_hdmi_output_name);
+
  /**
   * drm_display_info_set_bus_formats - set the supported bus formats
   * @info: display info to store bus formats in
@@ -789,6 +813,13 @@ int drm_connector_create_standard_properties(struct drm_device *dev)
  		return -ENOMEM;
  	dev->mode_config.link_status_property = prop;
  
+	prop = drm_property_create_enum(dev, 0, "hdmi_output_format",
+					drm_hdmi_output_enum_list,
+					ARRAY_SIZE(drm_hdmi_output_enum_list));
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.hdmi_output_property = prop;
+
  	return 0;
  }
  
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 4545c6e..e872a88 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -300,6 +300,17 @@ struct drm_tv_connector_state {
  	unsigned int hue;
  };
  
+/* HDMI output pixel format */
+enum drm_hdmi_output_type {
+	DRM_HDMI_OUTPUT_DEFAULT_RGB, /* default RGB */
+	DRM_HDMI_OUTPUT_YCBCR422, /* YCBCR 422 */
+	DRM_HDMI_OUTPUT_YCBCR444, /* YCBCR 444 */
+	DRM_HDMI_OUTPUT_YCBCR420, /* YCBCR 420 */
+	DRM_HDMI_OUTPUT_YCBCR_HQ, /* Highest subsampled YUV */
+	DRM_HDMI_OUTPUT_YCBCR_LQ, /* Lowest subsampled YUV */
+	DRM_HDMI_OUTPUT_INVALID, /* Guess what ? */
+};
+
  /**
   * struct drm_connector_state - mutable connector state
   * @connector: backpointer to the connector
@@ -329,6 +340,8 @@ struct drm_connector_state {
  	struct drm_atomic_state *state;
  
  	struct drm_tv_connector_state tv;
+
+	enum drm_hdmi_output_type hdmi_output;
  };
  
  /**
@@ -945,6 +958,7 @@ static inline void drm_connector_unreference(struct drm_connector *connector)
  
  const char *drm_get_connector_status_name(enum drm_connector_status status);
  const char *drm_get_subpixel_order_name(enum subpixel_order order);
+const char *drm_get_hdmi_output_name(enum drm_hdmi_output_type type);
  const char *drm_get_dpms_name(int val);
  const char *drm_get_dvi_i_subconnector_name(int val);
  const char *drm_get_dvi_i_select_name(int val);
diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
index 4298171..1887261 100644
--- a/include/drm/drm_mode_config.h
+++ b/include/drm/drm_mode_config.h
@@ -740,6 +740,11 @@ struct drm_mode_config {
  	 * the position of the output on the host's screen.
  	 */
  	struct drm_property *suggested_y_property;
+	/**
+	 * @hdmi_output_property: output pixel format from HDMI display
+	 * Default is set for RGB
+	 */
+	struct drm_property *hdmi_output_property;
  
  	/* dumb ioctl parameters */
  	uint32_t preferred_depth, prefer_shadow;

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