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drm/amd/display: Add work around for tunneled MST. 

[Why]
Certain USB4 docks do not seem to be able to handle disabling
DSC once it has been enabled on an MST stream. This can result
in blank displays.

[How]
As a work around, always enable DSC on docks exhibiting this issue. The
flag to indicate the use of DSC for MST streams on a USB4 dock is set
during detection of the dock and only cleared when the USB4 dock is
disconnected.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Jimmy Kizito 2021-11-14 21:48:02 -05:00 committed by Alex Deucher
parent 5ceaebcda9
commit c9beecc5c9
4 changed files with 30 additions and 11 deletions
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16
drivers/gpu/drm/amd/display/dc/core/dc_link.c
View File

@ -758,6 +758,18 @@ static bool detect_dp(struct dc_link *link,
dal_ddc_service_set_transaction_type(link->ddc,
sink_caps->transaction_type);
#if defined(CONFIG_DRM_AMD_DC_DCN)
/* Apply work around for tunneled MST on certain USB4 docks. Always use DSC if dock
* reports DSC support.
*/
if (link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA &&
link->type == dc_connection_mst_branch &&
link->dpcd_caps.branch_dev_id == DP_BRANCH_DEVICE_ID_90CC24 &&
link->dpcd_caps.dsc_caps.dsc_basic_caps.fields.dsc_support.DSC_SUPPORT &&
!link->dc->debug.dpia_debug.bits.disable_mst_dsc_work_around)
link->wa_flags.dpia_mst_dsc_always_on = true;
#endif
#if defined(CONFIG_DRM_AMD_DC_HDCP)
/* In case of fallback to SST when topology discovery below fails
* HDCP caps will be querried again later by the upper layer (caller
@ -1203,6 +1215,10 @@ static bool dc_link_detect_helper(struct dc_link *link,
LINK_INFO("link=%d, mst branch is now Disconnected\n",
link->link_index);
/* Disable work around which keeps DSC on for tunneled MST on certain USB4 docks. */
if (link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA)
link->wa_flags.dpia_mst_dsc_always_on = false;
dm_helpers_dp_mst_stop_top_mgr(link->ctx, link);
link->mst_stream_alloc_table.stream_count = 0;

20
drivers/gpu/drm/amd/display/dc/core/dc_resource.c
View File

@ -2256,16 +2256,6 @@ enum dc_status dc_validate_global_state(
if (!new_ctx)
return DC_ERROR_UNEXPECTED;
#if defined(CONFIG_DRM_AMD_DC_DCN)
/*
* Update link encoder to stream assignment.
* TODO: Split out reason allocation from validation.
*/
if (dc->res_pool->funcs->link_encs_assign && fast_validate == false)
dc->res_pool->funcs->link_encs_assign(
dc, new_ctx, new_ctx->streams, new_ctx->stream_count);
#endif
if (dc->res_pool->funcs->validate_global) {
result = dc->res_pool->funcs->validate_global(dc, new_ctx);
@ -2317,6 +2307,16 @@ enum dc_status dc_validate_global_state(
if (!dc->res_pool->funcs->validate_bandwidth(dc, new_ctx, fast_validate))
result = DC_FAIL_BANDWIDTH_VALIDATE;
#if defined(CONFIG_DRM_AMD_DC_DCN)
/*
* Only update link encoder to stream assignment after bandwidth validation passed.
* TODO: Split out assignment and validation.
*/
if (result == DC_OK && dc->res_pool->funcs->link_encs_assign && fast_validate == false)
dc->res_pool->funcs->link_encs_assign(
dc, new_ctx, new_ctx->streams, new_ctx->stream_count);
#endif
return result;
}

3
drivers/gpu/drm/amd/display/dc/dc.h
View File

@ -508,7 +508,8 @@ union dpia_debug_options {
uint32_t disable_dpia:1;
uint32_t force_non_lttpr:1;
uint32_t extend_aux_rd_interval:1;
uint32_t reserved:29;
uint32_t disable_mst_dsc_work_around:1;
uint32_t reserved:28;
} bits;
uint32_t raw;
};

2
drivers/gpu/drm/amd/display/dc/dc_link.h
View File

@ -191,6 +191,8 @@ struct dc_link {
bool dp_skip_DID2;
bool dp_skip_reset_segment;
bool dp_mot_reset_segment;
/* Some USB4 docks do not handle turning off MST DSC once it has been enabled. */
bool dpia_mst_dsc_always_on;
} wa_flags;
struct link_mst_stream_allocation_table mst_stream_alloc_table;