[PATCH v6 7/9] drm: Expose modes with aspect ratio, only if requested

[Nautiyal, Ankit K]

From: Ankit Nautiyal <ankit.k.nautiyal at intel.com>

We parse the EDID and add all the modes in the connector's modelist.
This adds CEA modes with aspect ratio information too, regadless of
whether user space requested this information or not.

This patch prunes the modes with aspect-ratio information, from a
connector's modelist, if the user-space has not set the aspect ratio
DRM client cap.

Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
Cc: Shashank Sharma <shashank.sharma at intel.com>
Cc: Jose Abreu <jose.abreu at synopsys.com>

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>

V3: As suggested by Ville, modified the mechanism of pruning of modes
    with aspect-ratio, if the aspect-ratio is not supported. Instead
    of straight away pruning such a mode, the mode is retained with
    aspect ratio bits set to zero, provided it is unique.
V4: rebase
V5: Addressed review comments from Ville:
    -used a pointer to store last valid mode.
    -avoided, modifying of picture_aspect_ratio in kernel mode,
     instead only flags bits of user mode are reset (if aspect-ratio
     is not supported).
V6: As suggested by Ville, corrected the mode pruning logic and
    elaborated the mode pruning logic and the assumptions taken.
---
 drivers/gpu/drm/drm_connector.c | 40 ++++++++++++++++++++++++++++++++++++----
 1 file changed, 36 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index b3cde89..4561239 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -1531,8 +1531,10 @@ static struct drm_encoder *drm_connector_get_encoder(struct drm_connector *conne
 	return connector->encoder;
 }
 
-static bool drm_mode_expose_to_userspace(const struct drm_display_mode *mode,
-					 const struct drm_file *file_priv)
+static bool
+drm_mode_expose_to_userspace(const struct drm_display_mode *mode,
+			     const struct drm_display_mode *last_mode,
+			     const struct drm_file *file_priv)
 {
 	/*
 	 * If user-space hasn't configured the driver to expose the stereo 3D
@@ -1540,6 +1542,26 @@ static bool drm_mode_expose_to_userspace(const struct drm_display_mode *mode,
 	 */
 	if (!file_priv->stereo_allowed && drm_mode_is_stereo(mode))
 		return false;
+	/*
+	 * If user-space hasn't configured the driver to expose the modes with
+	 * aspect-ratio, don't expose them. But in case of a unique mode, let
+	 * the mode be passed, so that it can be enumerated with aspect-ratio
+	 * bits erased.
+	 *
+	 * It is assumed here, that the list of modes for a given connector, is
+	 * sorted, such that modes that have different aspect-ratios, but are
+	 * otherwise identical, are back to back.
+	 * This way, saving the last valid mode, and matching it with the
+	 * current mode will help in determining, if the current mode is unique.
+	 */
+	if (!file_priv->aspect_ratio_allowed &&
+	    mode->picture_aspect_ratio != HDMI_PICTURE_ASPECT_NONE &&
+	    last_mode && drm_mode_match(mode, last_mode,
+					DRM_MODE_MATCH_TIMINGS |
+					DRM_MODE_MATCH_CLOCK |
+					DRM_MODE_MATCH_FLAGS |
+					DRM_MODE_MATCH_3D_FLAGS))
+		return false;
 
 	return true;
 }
@@ -1551,6 +1573,7 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
 	struct drm_connector *connector;
 	struct drm_encoder *encoder;
 	struct drm_display_mode *mode;
+	struct drm_display_mode *last_valid_mode;
 	int mode_count = 0;
 	int encoders_count = 0;
 	int ret = 0;
@@ -1606,9 +1629,13 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
 	out_resp->connection = connector->status;
 
 	/* delayed so we get modes regardless of pre-fill_modes state */
+	last_valid_mode = NULL;
 	list_for_each_entry(mode, &connector->modes, head)
-		if (drm_mode_expose_to_userspace(mode, file_priv))
+		if (drm_mode_expose_to_userspace(mode, last_valid_mode,
+						 file_priv)) {
 			mode_count++;
+			last_valid_mode = mode;
+		}
 
 	/*
 	 * This ioctl is called twice, once to determine how much space is
@@ -1617,11 +1644,15 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
 	if ((out_resp->count_modes >= mode_count) && mode_count) {
 		copied = 0;
 		mode_ptr = (struct drm_mode_modeinfo __user *)(unsigned long)out_resp->modes_ptr;
+		last_valid_mode = NULL;
 		list_for_each_entry(mode, &connector->modes, head) {
-			if (!drm_mode_expose_to_userspace(mode, file_priv))
+			if (!drm_mode_expose_to_userspace(mode,
+							  last_valid_mode,
+							  file_priv))
 				continue;
 
 			drm_mode_convert_to_umode(&u_mode, mode);
+			drm_mode_handle_aspect_ratio(file_priv, &u_mode.flags);
 			if (copy_to_user(mode_ptr + copied,
 					 &u_mode, sizeof(u_mode))) {
 				ret = -EFAULT;
@@ -1629,6 +1660,7 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
 
 				goto out;
 			}
+			last_valid_mode = mode;
 			copied++;
 		}
 	}
-- 
2.7.4