drm: provide a helper for the encoder possible_crtcs mask
The encoder possible_crtcs mask identifies which CRTCs can be bound to
a particular encoder. Each bit from bit 0 defines an index in the list
of CRTCs held in the DRM mode_config crtc_list. Rather than having
drivers trying to track the position of their CRTCs in the list, expose
the code which already exists for calculating the appropriate mask bit
for a CRTC.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
[treding@nvidia.com: add drm_crtc_index(), move to core]
Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index d6cf77c..452bcbd 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -675,6 +675,29 @@
EXPORT_SYMBOL(drm_crtc_cleanup);
/**
+ * drm_crtc_index - find the index of a registered CRTC
+ * @crtc: CRTC to find index for
+ *
+ * Given a registered CRTC, return the index of that CRTC within a DRM
+ * device's list of CRTCs.
+ */
+unsigned int drm_crtc_index(struct drm_crtc *crtc)
+{
+ unsigned int index = 0;
+ struct drm_crtc *tmp;
+
+ list_for_each_entry(tmp, &crtc->dev->mode_config.crtc_list, head) {
+ if (tmp == crtc)
+ return index;
+
+ index++;
+ }
+
+ BUG();
+}
+EXPORT_SYMBOL(drm_crtc_index);
+
+/**
* drm_mode_probed_add - add a mode to a connector's probed mode list
* @connector: connector the new mode
* @mode: mode data