Merge tag 'drm-intel-next-2024-02-27-1' of git://anongit.freedesktop.org/drm/drm...

[thirdparty/linux.git] / drivers / gpu / drm / display / drm_dp_helper.c

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index 8d6ce46471ae6161c601ae0488fb65dda48f396b..d046dfa79504f9c5368aaf2a0bd87c2e1d84f4b7 100644 (file)
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -4055,3 +4055,33 @@ int drm_dp_bw_channel_coding_efficiency(bool is_uhbr)
                return 800000;
 }
 EXPORT_SYMBOL(drm_dp_bw_channel_coding_efficiency);
+
+/**
+ * drm_dp_max_dprx_data_rate - Get the max data bandwidth of a DPRX sink
+ * @max_link_rate: max DPRX link rate in 10kbps units
+ * @max_lanes: max DPRX lane count
+ *
+ * Given a link rate and lanes, get the data bandwidth.
+ *
+ * Data bandwidth is the actual payload rate, which depends on the data
+ * bandwidth efficiency and the link rate.
+ *
+ * Note that protocol layers above the DPRX link level considered here can
+ * further limit the maximum data rate. Such layers are the MST topology (with
+ * limits on the link between the source and first branch device as well as on
+ * the whole MST path until the DPRX link) and (Thunderbolt) DP tunnels -
+ * which in turn can encapsulate an MST link with its own limit - with each
+ * SST or MST encapsulated tunnel sharing the BW of a tunnel group.
+ *
+ * Returns the maximum data rate in kBps units.
+ */
+int drm_dp_max_dprx_data_rate(int max_link_rate, int max_lanes)
+{
+       int ch_coding_efficiency =
+               drm_dp_bw_channel_coding_efficiency(drm_dp_is_uhbr_rate(max_link_rate));
+
+       return DIV_ROUND_DOWN_ULL(mul_u32_u32(max_link_rate * 10 * max_lanes,
+                                             ch_coding_efficiency),
+                                 1000000 * 8);
+}
+EXPORT_SYMBOL(drm_dp_max_dprx_data_rate);