drm: add clone mode check for CRTC

Add a common helper to check if the given CRTC state is in clone mode.
This can be used by drivers to help detect if a CRTC is being shared by
multiple encoders

Signed-off-by: Jessica Zhang <[email protected]>
Reviewed-by: Abhinav Kumar <[email protected]>
Reviewed-by: Maxime Ripard <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Dmitry Baryshkov <[email protected]>

Author: Jessica Zhang

drivers/gpu/drm/drm_crtc.c

@@ -939,3 +939,23 @@ int drm_crtc_create_scaling_filter_property(struct drm_crtc *crtc,
 	return 0;
 }
 EXPORT_SYMBOL(drm_crtc_create_scaling_filter_property);
+
+/**
+ * drm_crtc_in_clone_mode - check if the given CRTC state is in clone mode
+ *
+ * @crtc_state: CRTC state to check
+ *
+ * This function determines if the given CRTC state is being cloned by multiple
+ * encoders.
+ *
+ * RETURNS:
+ * True if the CRTC state is in clone mode. False otherwise
+ */
+bool drm_crtc_in_clone_mode(struct drm_crtc_state *crtc_state)
+{
+	if (!crtc_state)
+		return false;
+
+	return hweight32(crtc_state->encoder_mask) > 1;
+}
+EXPORT_SYMBOL(drm_crtc_in_clone_mode);

include/drm/drm_crtc.h

@@ -1323,5 +1323,5 @@ static inline struct drm_crtc *drm_crtc_find(struct drm_device *dev,
 
 int drm_crtc_create_scaling_filter_property(struct drm_crtc *crtc,
 					    unsigned int supported_filters);
-
+bool drm_crtc_in_clone_mode(struct drm_crtc_state *crtc_state);
 #endif /* __DRM_CRTC_H__ */