[PATCH v10 07/11] drm: Add helper functions to handle aspect-ratio flag bits

[Nautiyal, Ankit K]

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

This patch adds helper functions for determining if aspect-ratio is
expected in user-mode and for allowing/disallowing the aspect-ratio,
if its not expected.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
---
 drivers/gpu/drm/drm_modes.c | 47 +++++++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_modes.h     |  4 ++++
 2 files changed, 51 insertions(+)

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index c395a24..d6133e8 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1759,3 +1759,50 @@ bool drm_mode_is_420(const struct drm_display_info *display,
 		drm_mode_is_420_also(display, mode);
 }
 EXPORT_SYMBOL(drm_mode_is_420);
+
+/**
+ * drm_mode_aspect_ratio_allowed - checks if the aspect-ratio information
+ * is expected from the user-mode.
+ *
+ * If the user has set aspect-ratio cap, then the flag of the user-mode is
+ * allowed to contain aspect-ratio value.
+ * If the user does not set aspect-ratio cap, then the only value allowed in the
+ * flags bits is aspect-ratio NONE.
+ *
+ * @file_priv: file private structure to get the user capabilities
+ * @umode: drm_mode_modeinfo struct, whose flag carry the aspect ratio
+ * information.
+ *
+ * Returns:
+ * true if the aspect-ratio info is allowed in the user-mode flags.
+ * false, otherwise.
+ */
+bool
+drm_mode_aspect_ratio_allowed(const struct drm_file *file_priv,
+			      struct drm_mode_modeinfo *umode)
+{
+	return file_priv->aspect_ratio_allowed || (umode->flags &
+		DRM_MODE_FLAG_PIC_AR_MASK) == DRM_MODE_FLAG_PIC_AR_NONE;
+}
+EXPORT_SYMBOL(drm_mode_aspect_ratio_allowed);
+
+/**
+ * drm_mode_filter_aspect_ratio_flags - filters the aspect-ratio bits in the
+ * user-mode flags.
+ *
+ * Checks if the aspect-ratio information is allowed. Resets the aspect-ratio
+ * bits in the user-mode flags, if aspect-ratio info is not allowed.
+ *
+ * @file_priv: file private structure to get the user capabilities.
+ * @umode: drm_mode_modeinfo struct, whose flags' aspect-ratio bits needs to
+ * be filtered.
+ *
+ */
+void
+drm_mode_filter_aspect_ratio_flags(const struct drm_file *file_priv,
+				   struct drm_mode_modeinfo *umode)
+{
+	if (!drm_mode_aspect_ratio_allowed(file_priv, umode))
+		umode->flags &= ~DRM_MODE_FLAG_PIC_AR_MASK;
+}
+EXPORT_SYMBOL(drm_mode_filter_aspect_ratio_flags);
diff --git a/include/drm/drm_modes.h b/include/drm/drm_modes.h
index 2f78b7e..e0b060d 100644
--- a/include/drm/drm_modes.h
+++ b/include/drm/drm_modes.h
@@ -461,6 +461,10 @@ bool drm_mode_is_420_also(const struct drm_display_info *display,
 			  const struct drm_display_mode *mode);
 bool drm_mode_is_420(const struct drm_display_info *display,
 		     const struct drm_display_mode *mode);
+bool drm_mode_aspect_ratio_allowed(const struct drm_file *file_priv,
+				   struct drm_mode_modeinfo *umode);
+void drm_mode_filter_aspect_ratio_flags(const struct drm_file *file_priv,
+					struct drm_mode_modeinfo *umode);
 
 struct drm_display_mode *drm_cvt_mode(struct drm_device *dev,
 				      int hdisplay, int vdisplay, int vrefresh,
-- 
2.7.4