@@ -3855,6 +3855,27 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
if (intel_dp->dpcd[DP_DPCD_REV] == 0)
return false; /* DPCD not present */
+ if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_SINK_COUNT,
+ &intel_dp->sink_count, 1) < 0)
+ return false;
+
+ /*
+ * Sink count can change between short pulse hpd hence
+ * a member variable in intel_dp will track any changes
+ * between short pulse interrupts.
+ */
+ intel_dp->sink_count = DP_GET_SINK_COUNT(intel_dp->sink_count);
+
+ /*
+ * SINK_COUNT == 0 and DOWNSTREAM_PORT_PRESENT == 1 implies that
+ * a dongle is present but no display. Unless we require to know
+ * if a dongle is present or not, we don't need to update
+ * downstream port information. So, an early return here saves
+ * time from performing other operations which are not required.
+ */
+ if (!intel_dp->sink_count)
+ return false;
+
/* Check if the panel supports PSR */
memset(intel_dp->psr_dpcd, 0, sizeof(intel_dp->psr_dpcd));
if (is_edp(intel_dp)) {
@@ -4372,14 +4393,9 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp)
/* If we're HPD-aware, SINK_COUNT changes dynamically */
if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
intel_dp->downstream_ports[0] & DP_DS_PORT_HPD) {
- uint8_t reg;
-
- if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_SINK_COUNT,
- ®, 1) < 0)
- return connector_status_unknown;
- return DP_GET_SINK_COUNT(reg) ? connector_status_connected
- : connector_status_disconnected;
+ return intel_dp->sink_count ?
+ connector_status_connected : connector_status_disconnected;
}
/* If no HPD, poke DDC gently */
@@ -774,6 +774,7 @@ struct intel_dp {
uint32_t DP;
int link_rate;
uint8_t lane_count;
+ uint8_t sink_count;
bool has_audio;
enum hdmi_force_audio force_audio;
bool limited_color_range;
This patch reads sink_count dpcd always and removes its read operation based on values in downstream port dpcd. SINK_COUNT dpcd is not dependent on DOWNSTREAM_PORT_PRESENT dpcd. SINK_COUNT denotes if a display is attached, while DOWNSTREAM_PORT_PRESET indicates how many ports are available in the dongle where display can be attached. so it is possible for sink count to change irrespective of value in downstream port dpcd. Here is a table of possible values and scenarios sink_count downstream_port present 0 0 no display is attached 0 1 dongle is connected without display 1 0 display connected directly 1 1 display connected through dongle v2: Storing value of intel_dp->sink_count that is ready for consumption. (Ander) Squashing two commits into one. (Ander) v3: Added comment to explain the need of early return when sink count is 0. (Ander) Tested-by: Nathan D Ciobanu <nathan.d.ciobanu@intel.com> Signed-off-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com> Signed-off-by: Shubhangi Shrivastava <shubhangi.shrivastava@intel.com> --- drivers/gpu/drm/i915/intel_dp.c | 30 +++++++++++++++++++++++------- drivers/gpu/drm/i915/intel_drv.h | 1 + 2 files changed, 24 insertions(+), 7 deletions(-)