6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Arthur Heymans [ Upstream commit 5e08102d1d336593160d1434261d50b0c0f6cbe6 ] 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 (cherry picked from commit ccb6c2702033f1002b45807fb3cc938760f26f78) Cc: stable@vger.kernel.org # 6.4.x [ sashal: Applied the ASSR guard in perform_link_training_with_retries() instead of the absent edp_set_panel_assr() helper. ] Signed-off-by: Sasha Levin --- drivers/gpu/drm/amd/display/dc/dc.h | 1 + .../gpu/drm/amd/display/dc/link/protocols/link_dp_training.c | 3 ++- .../drm/amd/display/dc/link/protocols/link_edp_panel_control.c | 1 + 3 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 88e64b280c90f..1f4292336692e 100644 --- a/drivers/gpu/drm/amd/display/dc/dc.h +++ b/drivers/gpu/drm/amd/display/dc/dc.h @@ -1512,6 +1512,7 @@ struct dc_link { 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_dp_training.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c index 539f57858dfec..aa46e0e84ce4f 100644 --- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c +++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c @@ -1608,7 +1608,8 @@ bool perform_link_training_with_retries( */ bool result; 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; } } 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 d4d92da153ece..9f7ace40092ba 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 @@ -88,6 +88,7 @@ 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("Link: %d eDP panel mode supported: %d " "eDP panel mode enabled: %d \n", link->link_index, -- 2.53.0