drm: Helper to read max bits per component
Helper routine to read out maximum supported bits per
component for DisplayPort legay converters.
v2: Return early if detailed port cap info is not available.
Replace if-else ladder with switch-case (Ville)
Reviewed-by: Jim Bride <jim.bride@linux.intel.com>
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1473419458-17080-5-git-send-email-mika.kahola@intel.com
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index f171fbf..57c61d1 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -471,6 +471,48 @@
}
EXPORT_SYMBOL(drm_dp_downstream_max_clock);
+/**
+ * drm_dp_downstream_max_bpc() - extract branch device max
+ * bits per component
+ * @dpcd: DisplayPort configuration data
+ * @port_cap: port capabilities
+ *
+ * Returns max bpc on success or 0 if max bpc not defined
+ */
+int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const u8 port_cap[4])
+{
+ int type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
+ bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
+ DP_DETAILED_CAP_INFO_AVAILABLE;
+ int bpc;
+
+ if (!detailed_cap_info)
+ return 0;
+
+ switch (type) {
+ case DP_DS_PORT_TYPE_VGA:
+ case DP_DS_PORT_TYPE_DVI:
+ case DP_DS_PORT_TYPE_HDMI:
+ case DP_DS_PORT_TYPE_DP_DUALMODE:
+ bpc = port_cap[2] & DP_DS_MAX_BPC_MASK;
+
+ switch (bpc) {
+ case DP_DS_8BPC:
+ return 8;
+ case DP_DS_10BPC:
+ return 10;
+ case DP_DS_12BPC:
+ return 12;
+ case DP_DS_16BPC:
+ return 16;
+ }
+ default:
+ return 0;
+ }
+}
+EXPORT_SYMBOL(drm_dp_downstream_max_bpc);
+
/*
* I2C-over-AUX implementation
*/
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 60dd9dc..f3d1424 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -817,6 +817,8 @@
int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link);
int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4]);
+int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const u8 port_cap[4]);
void drm_dp_aux_init(struct drm_dp_aux *aux);
int drm_dp_aux_register(struct drm_dp_aux *aux);