[PATCH 04/17] drm/amd/display: Add HDMI RR and SCDC skips

[<Roman.Li@amd.com>]

From: Ilya Bakoulin <Ilya.Bakoulin@amd.com>

[Why/How]
- Add debug key to avoid enabling RR by default.
- Skip SCDC access if sink or SCDC cap not present

Reviewed-by: Relja (Reggie) Vojvodic <relja.vojvodic@amd.com>
Reviewed-by: Chris Park <chris.park@amd.com>
Signed-off-by: Ilya Bakoulin <Ilya.Bakoulin@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
---
 drivers/gpu/drm/amd/display/dc/dc.h                      | 1 +
 drivers/gpu/drm/amd/display/dc/link/link_detection.c     | 4 +++-
 drivers/gpu/drm/amd/display/dc/link/protocols/link_ddc.c | 9 ++++++++-
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dc.h b/drivers/gpu/drm/amd/display/dc/dc.h
index bed0daeb0c6f..d2256c454424 100644
--- a/drivers/gpu/drm/amd/display/dc/dc.h
+++ b/drivers/gpu/drm/amd/display/dc/dc.h
@@ -1293,6 +1293,7 @@ struct dc_debug_options {
 	union fw_assisted_mclk_switch_version fams_version;
 	union dmub_fams2_global_feature_config fams2_config;
 	bool fams2_imm_restore_drr;
+	bool skip_hdmi_rr_enable;
 	unsigned int force_cositing;
 	unsigned int disable_spl;
 	unsigned int force_easf;
diff --git a/drivers/gpu/drm/amd/display/dc/link/link_detection.c b/drivers/gpu/drm/amd/display/dc/link/link_detection.c
index 12fd4fd24a90..b4546f93af0c 100644
--- a/drivers/gpu/drm/amd/display/dc/link/link_detection.c
+++ b/drivers/gpu/drm/amd/display/dc/link/link_detection.c
@@ -1391,8 +1391,10 @@ static bool detect_link_and_local_sink(struct dc_link *link,
 			read_idcc_data(link->ddc, HDMI_IDCC_SCOPE_RW_CA,
 				link->hdmi_cable_id.raw, 0, 4);
 		}
-		if (sink->edid_caps.rr_capable)
+
+		if (sink->edid_caps.rr_capable && !dc->debug.skip_hdmi_rr_enable)
 			hdmi_frl_write_read_request_enable(link->ddc);
+
 		/* When FreeSync is toggled through OSD,
 		 * we see same EDID no matter what. Check MCCS caps
 		 * to see if we should update FreeSync caps now.
diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_ddc.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_ddc.c
index d87f6f377d06..3fbfc6e2594b 100644
--- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_ddc.c
+++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_ddc.c
@@ -580,6 +580,9 @@ void write_scdc_data(struct ddc_service *ddc_service,
 	uint8_t write_buffer[2] = {0};
 	/*Lower than 340 Scramble bit from SCDC caps*/
 
+	if (!ddc_service->link->local_sink)
+		return;
+
 	if (ddc_service->link->local_sink &&
 		(ddc_service->link->local_sink->edid_caps.panel_patch.skip_scdc_overwrite ||
 		!ddc_service->link->local_sink->edid_caps.scdc_present))
@@ -617,8 +620,12 @@ void read_scdc_data(struct ddc_service *ddc_service)
 	uint8_t offset = HDMI_SCDC_TMDS_CONFIG;
 	uint8_t tmds_config = 0;
 
+	if (!ddc_service->link->local_sink)
+		return;
+
 	if (ddc_service->link->local_sink &&
-		ddc_service->link->local_sink->edid_caps.panel_patch.skip_scdc_overwrite)
+			(ddc_service->link->local_sink->edid_caps.panel_patch.skip_scdc_overwrite ||
+			!ddc_service->link->local_sink->edid_caps.scdc_present))
 		return;
 
 	link_query_ddc_data(ddc_service, slave_address, &offset,
-- 
2.34.1