From c9beecc5c9626ab772160ab3f8e209abc09fa54d Mon Sep 17 00:00:00 2001 From: Jimmy Kizito Date: Sun, 14 Nov 2021 21:48:02 -0500 Subject: [PATCH] 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 Reviewed-by: Aric Cyr Acked-by: Bhawanpreet Lakha Signed-off-by: Jimmy Kizito Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/display/dc/core/dc_link.c | 16 +++++++++++++++ .../gpu/drm/amd/display/dc/core/dc_resource.c | 20 +++++++++---------- drivers/gpu/drm/amd/display/dc/dc.h | 3 ++- drivers/gpu/drm/amd/display/dc/dc_link.h | 2 ++ 4 files changed, 30 insertions(+), 11 deletions(-) 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 60544788e911..c8457babfdea 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c @@ -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; diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c index dcbfae210493..e2d9a46d0e1a 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c @@ -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; } diff --git a/drivers/gpu/drm/amd/display/dc/dc.h b/drivers/gpu/drm/amd/display/dc/dc.h index 3aac3f4a2852..618e7989176f 100644 --- a/drivers/gpu/drm/amd/display/dc/dc.h +++ b/drivers/gpu/drm/amd/display/dc/dc.h @@ -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; }; diff --git a/drivers/gpu/drm/amd/display/dc/dc_link.h b/drivers/gpu/drm/amd/display/dc/dc_link.h index 180ecd860296..b01077a6af0e 100644 --- a/drivers/gpu/drm/amd/display/dc/dc_link.h +++ b/drivers/gpu/drm/amd/display/dc/dc_link.h @@ -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;