From 3f34c344acb29279122393222e643b5540dc24e3 Mon Sep 17 00:00:00 2001
From: Jimmy Kizito <Jimmy.Kizito@amd.com>
Date: Tue, 14 Sep 2021 11:37:04 -0400
Subject: drm/amd/display: Add workaround flag for EDID read on certain docks
Git-commit: 4b169ca3674919756e76616dc65a79114962ea14
Patch-mainline: v5.16-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
[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@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
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 a1fa50ddf43e..27b9ff98a569 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 b991ba1d6f9a..180ecd860296 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;
--
2.38.1