[PATCH 06/20] drm: add helper to validate YCBCR420 modes

[Shashank Sharma]

YCBCR420 modes are supported only on HDMI 2.0 capable sources.
This patch adds:
- A drm helper to validate YCBCR420-only mode on a particular
  connector. This function will help pruning the YCBCR420-only
  modes from the connector's modelist.
- A bool variable (ycbcr_420_allowed) in the drm connector structure.
  While handling the EDID from HDMI 2.0 sinks, its important to know
  if the source is capable of handling YCBCR420 output, so that no
  YCBCR 420 modes will be listed for sources which can't handle it.
  A driver should set this variable if it wants to see YCBCR420 modes
  in the modedb.

V5: Introduced the patch in series.
V5-resend: Squashed two patches (validate YCBCR420 and add YCBCR420
	   identifier)

Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
---
 drivers/gpu/drm/drm_edid.c         |  3 ++-
 drivers/gpu/drm/drm_modes.c        | 28 ++++++++++++++++++++++++++++
 drivers/gpu/drm/drm_probe_helper.c |  4 ++++
 include/drm/drm_connector.h        |  9 +++++++++
 include/drm/drm_edid.h             |  1 +
 include/drm/drm_modes.h            |  5 +++++
 6 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 10dab62..44be128 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2950,10 +2950,11 @@ u8 drm_match_cea_mode(const struct drm_display_mode *to_match)
 }
 EXPORT_SYMBOL(drm_match_cea_mode);
 
-static bool drm_valid_cea_vic(u8 vic)
+bool drm_valid_cea_vic(u8 vic)
 {
 	return vic > 0 && vic < ARRAY_SIZE(edid_cea_modes);
 }
+EXPORT_SYMBOL(drm_valid_cea_vic);
 
 /**
  * drm_get_cea_aspect_ratio - get the picture aspect ratio corresponding to
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index f2493b9..3b53c8e3 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1083,6 +1083,34 @@ drm_mode_validate_size(const struct drm_display_mode *mode,
 }
 EXPORT_SYMBOL(drm_mode_validate_size);
 
+/**
+ * drm_mode_ycbcr420_only - add 'ycbcr420-only' modes only when allowed
+ * @mode: mode to check
+ * @connector: drm connector under action
+ *
+ * This function is a helper which can be used to filter out any YCBCR420
+ * only mode, when the source doesn't support it.
+ *
+ * Returns:
+ * The mode status
+ */
+enum drm_mode_status
+drm_mode_validate_ycbcr420(const struct drm_display_mode *mode,
+			   struct drm_connector *connector)
+{
+	u8 vic = drm_match_cea_mode(mode);
+	enum drm_mode_status status = MODE_OK;
+	struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
+
+	if (drm_valid_cea_vic(vic) && test_bit(vic, hdmi->y420_vdb_modes)) {
+		if (!connector->ycbcr_420_allowed)
+			status = MODE_NO_420;
+	}
+
+	return status;
+}
+EXPORT_SYMBOL(drm_mode_validate_ycbcr420);
+
 #define MODE_STATUS(status) [MODE_ ## status + 3] = #status
 
 static const char * const drm_mode_status_names[] = {
diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 00e6832..904966c 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -528,6 +528,10 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 		if (mode->status == MODE_OK)
 			mode->status = drm_mode_validate_pipeline(mode,
 								  connector);
+
+		if (mode->status == MODE_OK)
+			mode->status = drm_mode_validate_ycbcr420(mode,
+								  connector);
 	}
 
 prune:
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index b3af8e3..225e092 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -746,6 +746,15 @@ struct drm_connector {
 	bool interlace_allowed;
 	bool doublescan_allowed;
 	bool stereo_allowed;
+
+	/**
+	 * @ycbcr_420_allowed : This bool indicates if this connector is
+	 * capable of handling YCBCR 420 output. While parsing the EDID
+	 * blocks, its very helpful to know, if the source is capable of
+	 * handling YCBCR 420 outputs.
+	 */
+	bool ycbcr_420_allowed;
+
 	/**
 	 * @registered: Is this connector exposed (registered) with userspace?
 	 * Protected by @mutex.
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index 89c0062..b55b2a7 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -477,4 +477,5 @@ void drm_edid_get_monitor_name(struct edid *edid, char *name,
 struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
 					   int hsize, int vsize, int fresh,
 					   bool rb);
+bool drm_valid_cea_vic(u8 vic);
 #endif /* __DRM_EDID_H__ */
diff --git a/include/drm/drm_modes.h b/include/drm/drm_modes.h
index 94ac771..f8a1268 100644
--- a/include/drm/drm_modes.h
+++ b/include/drm/drm_modes.h
@@ -80,6 +80,7 @@ struct videomode;
  * @MODE_ONE_SIZE: only one resolution is supported
  * @MODE_NO_REDUCED: monitor doesn't accept reduced blanking
  * @MODE_NO_STEREO: stereo modes not supported
+ * @MODE_NO_420: ycbcr 420 modes not supported
  * @MODE_STALE: mode has become stale
  * @MODE_BAD: unspecified reason
  * @MODE_ERROR: error condition
@@ -124,6 +125,7 @@ enum drm_mode_status {
 	MODE_ONE_SIZE,
 	MODE_NO_REDUCED,
 	MODE_NO_STEREO,
+	MODE_NO_420,
 	MODE_STALE = -3,
 	MODE_BAD = -2,
 	MODE_ERROR = -1
@@ -496,6 +498,9 @@ bool drm_mode_equal_no_clocks_no_stereo(const struct drm_display_mode *mode1,
 enum drm_mode_status drm_mode_validate_basic(const struct drm_display_mode *mode);
 enum drm_mode_status drm_mode_validate_size(const struct drm_display_mode *mode,
 					    int maxX, int maxY);
+enum drm_mode_status
+drm_mode_validate_ycbcr420(const struct drm_display_mode *mode,
+			   struct drm_connector *connector);
 void drm_mode_prune_invalid(struct drm_device *dev,
 			    struct list_head *mode_list, bool verbose);
 void drm_mode_sort(struct list_head *mode_list);
-- 
2.7.4