[PATCH] drm/amd/display: Keep eDP Vdd on when eDP stream is already

[Liu, Zhan]

[Public]

[Why]
Even if can_apply_edp_fast_boot is set to 1 at boot, this flag will
be cleared to 0 at S3 resume. However, we still need to keep Vdd on
at S3 resume. Turning eDP Vdd off at resume will result in black
screen at S3 resume.

[How]
Don't turn eDP Vdd off when there is an existing eDP stream. This can
assure eDP display come back after S3.

Signed-off-by: Zhan Liu <zhan.liu at amd.com>
---
 .../display/dc/dce110/dce110_hw_sequencer.c   | 23 +++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
index 72dd41e7a7d6..1aa6f2737534 100644
--- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
@@ -1796,9 +1796,28 @@ void dce110_enable_accelerated_mode(struct dc *dc, struct dc_state *context)
                                break;
                        }
                }
-               // We are trying to enable eDP, don't power down VDD
-               if (can_apply_edp_fast_boot)
+
+               /*
+                * TO-DO: So far the code logic below only addresses single eDP case.
+                * For dual eDP case, there are a few things that need to be
+                * implemented first:
+                *
+                * 1. Change the fastboot logic above, so eDP link[0 or 1]'s
+                * stream[0 or 1] will all be checked.
+                *
+                * 2. Change keep_edp_vdd_on to an array, and maintain keep_edp_vdd_on
+                * for each eDP.
+                *
+                * Once above 2 things are completed, we can then change the logic below
+                * correspondingly, so dual eDP case will be fully covered.
+                */
+
+               // We are trying to enable eDP, don't power down VDD if there is an existing eDP stream
+               if ((edp_stream_num = 1 && edp_streams[0]) || can_apply_edp_fast_boot) {
                        keep_edp_vdd_on = true;
+                       DC_LOG_EVENT_LINK_TRAINING("At least 1 eDP stream is already enabled, will keep eDP Vdd on\n");
+               } else
+                       DC_LOG_EVENT_LINK_TRAINING("No eDP stream enabled, will turn eDP Vdd off\n");
        }

        // Check seamless boot support
--
2.25.1