From: Wesley Chalmers <Wesley.Chalmers@xxxxxxx>
[WHY]
SCR for DP 2.0 requires that LTTPR caps be read first on hotplug.
For the sake of consistency, this should also be the case on bootup.
Signed-off-by: Wesley Chalmers <Wesley.Chalmers@xxxxxxx>
Reviewed-by: Jun Lei <Jun.Lei@xxxxxxx>
Acked-by: Anson Jacob <Anson.Jacob@xxxxxxx>
---
drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c | 4 ++++
drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c | 3 +++
drivers/gpu/drm/amd/display/dc/inc/dc_link_dp.h | 1 +
3 files changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
index 3b175af97388..711ba953a99b 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
@@ -54,6 +54,7 @@
#include "dce/dmub_hw_lock_mgr.h"
#include "dc_trace.h"
#include "dce/dmub_outbox.h"
+#include "inc/dc_link_dp.h"
#define DC_LOGGER_INIT(logger)
@@ -1403,6 +1404,9 @@ void dcn10_init_hw(struct dc *dc)
if (dc->links[i]->connector_signal != SIGNAL_TYPE_DISPLAY_PORT)
continue;
+ /* DP 2.0 requires that LTTPR Caps be read first */
+ dp_retrieve_lttpr_cap(dc->links[i]);
+
/*
* If any of the displays are lit up turn them off.
* The reason is that some MST hubs cannot be turned off
diff --git a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
index ef5d0b778a72..6c88c5f236a7 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
@@ -48,6 +48,7 @@
#include "dc_dmub_srv.h"
#include "link_hwss.h"
#include "dpcd_defs.h"
+#include "inc/dc_link_dp.h"
@@ -529,6 +530,8 @@ void dcn30_init_hw(struct dc *dc)
for (i = 0; i < dc->link_count; i++) {
if (dc->links[i]->connector_signal != SIGNAL_TYPE_DISPLAY_PORT)
continue;
+ /* DP 2.0 states that LTTPR regs must be read first */
+ dp_retrieve_lttpr_cap(dc->links[i]);
/* if any of the displays are lit up turn them off */
status = core_link_read_dpcd(dc->links[i], DP_SET_POWER,
diff --git a/drivers/gpu/drm/amd/display/dc/inc/dc_link_dp.h b/drivers/gpu/drm/amd/display/dc/inc/dc_link_dp.h
index dd38dd63697f..e2b58ec9912d 100644
--- a/drivers/gpu/drm/amd/display/dc/inc/dc_link_dp.h
+++ b/drivers/gpu/drm/amd/display/dc/inc/dc_link_dp.h
@@ -190,4 +190,5 @@ enum dc_status dpcd_configure_lttpr_mode(
struct link_training_settings *lt_settings);
enum dp_link_encoding dp_get_link_encoding_format(const struct dc_link_settings *link_settings);
+bool dp_retrieve_lttpr_cap(struct dc_link *link);
#endif /* __DC_LINK_DP_H__ */
--
2.25.1
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