From: Jimmy Kizito <Jimmy.Kizito@xxxxxxx>
[Why]
Certain docks appear to NAK I2C writes to the segment pointer with the
MOT (middle of transaction) bit clear. This behaviour can cause EDID
reads from higher segments to fail.
[How]
Add workaround flag for links which connect to docks exhibiting this
issue.
Cc: Wayne Lin <wayne.lin@xxxxxxx>
Reviewed-by: Jun Lei <Jun.Lei@xxxxxxx>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@xxxxxxx>
---
drivers/gpu/drm/amd/display/dc/core/dc_link.c | 3 +++
drivers/gpu/drm/amd/display/dc/dc_link.h | 1 +
2 files changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index b36678669283..e475fbd4d341 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -1765,6 +1765,9 @@ static bool dc_link_construct_dpia(struct dc_link *link,
link->psr_settings.psr_version = DC_PSR_VERSION_UNSUPPORTED;
+ /* Some docks seem to NAK I2C writes to segment pointer with mot=0. */
+ link->wa_flags.dp_mot_reset_segment = true;
+
return true;
ddc_create_fail:
diff --git a/drivers/gpu/drm/amd/display/dc/dc_link.h b/drivers/gpu/drm/amd/display/dc/dc_link.h
index b975d1307eff..1327624548a3 100644
--- a/drivers/gpu/drm/amd/display/dc/dc_link.h
+++ b/drivers/gpu/drm/amd/display/dc/dc_link.h
@@ -190,6 +190,7 @@ struct dc_link {
bool dp_keep_receiver_powered;
bool dp_skip_DID2;
bool dp_skip_reset_segment;
+ bool dp_mot_reset_segment;
} wa_flags;
struct link_mst_stream_allocation_table mst_stream_alloc_table;
--
2.25.1
