From ccb6c2702033f1002b45807fb3cc938760f26f78 Mon Sep 17 00:00:00 2001 From: Arthur Heymans Date: Sat, 12 Sep 2026 17:11:37 +0200 Subject: [PATCH] drm/amd/display: Preserve eDP mode on initial ASSR failure Commit 56d8ce9d8c17 ("drm/amd/display: Apply correct panel mode when reinitializing hardware") made ASSR failure fall back to the default panel mode unless eDP mode had previously been applied. However, dc_link is zero-initialized and DP_PANEL_MODE_DEFAULT is zero. Before the first call to dp_set_panel_mode(), panel_mode therefore looks like a previously applied default mode. If ASSR setup fails during the first link training attempt, the driver incorrectly trains the eDP link using the default scrambling mode. On a Google Vilboz Chromebook running self-built coreboot firmware and PSP verstage, this leaves the panel mostly black with corrupted output along the top edge. Track whether panel_mode has actually been initialized, and only consult the saved mode after it has been applied. This retains the recovery behavior while preserving eDP mode during initial link training. Fixes: 56d8ce9d8c17 ("drm/amd/display: Apply correct panel mode when reinitializing hardware") Assisted-by: Pi:gpt-5.6-sol Reviewed-by: George Zhang Reviewed-by: Alex Hung Signed-off-by: Arthur Heymans Tested-by: Dan Wheeler Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/display/dc/dc.h | 1 + .../amd/display/dc/link/protocols/link_edp_panel_control.c | 4 +++- 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/display/dc/dc.h b/drivers/gpu/drm/amd/display/dc/dc.h index c8e6e949ce79..cd31d8b1a527 100644 --- a/drivers/gpu/drm/amd/display/dc/dc.h +++ b/drivers/gpu/drm/amd/display/dc/dc.h @@ -1909,6 +1909,7 @@ struct dc_scratch_space { struct ddc_service *ddc; enum dp_panel_mode panel_mode; + bool panel_mode_initialized; bool aux_mode; /* Private to DC core */ diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_edp_panel_control.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_edp_panel_control.c index e904c7dd320e..0e9b2b675eac 100644 --- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_edp_panel_control.c +++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_edp_panel_control.c @@ -93,6 +93,7 @@ void dp_set_panel_mode(struct dc_link *link, enum dp_panel_mode panel_mode) } link->panel_mode = panel_mode; + link->panel_mode_initialized = true; DC_LOG_DETECTION_DP_CAPS("%d eDP panel mode supported: %d, enabled: %d\n", link->link_index, link->dpcd_caps.panel_mode_edp, @@ -1322,7 +1323,8 @@ void edp_set_panel_assr(struct dc_link *link, struct pipe_ctx *pipe_ctx, result = cp_psp->funcs.enable_assr(cp_psp->handle, link); - if (!result && link->panel_mode != DP_PANEL_MODE_EDP) + if (!result && link->panel_mode_initialized && + link->panel_mode != DP_PANEL_MODE_EDP) *panel_mode = DP_PANEL_MODE_DEFAULT; } }