This is a note to let you know that I've just added the patch titled drm/amd/display: dsc mst 2 4K displays go dark with 2 lane HBR3 to the 5.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-amd-display-dsc-mst-2-4k-displays-go-dark-with-2-lane-hbr3.patch and it can be found in the queue-5.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 90517c9838602846daa0feec7b37382fed61b001 Mon Sep 17 00:00:00 2001 From: Hersen Wu <hersenwu@xxxxxxx> Date: Wed, 25 Aug 2021 16:27:47 -0400 Subject: drm/amd/display: dsc mst 2 4K displays go dark with 2 lane HBR3 From: Hersen Wu <hersenwu@xxxxxxx> commit 90517c9838602846daa0feec7b37382fed61b001 upstream. [Why] call stack of amdgpu dsc mst pbn, slot num calculation is as below: -compute_bpp_x16_from_target_bandwidth -decide_dsc_target_bpp_x16 -setup_dsc_config -dc_dsc_compute_bandwidth_range -compute_mst_dsc_configs_for_link -compute_mst_dsc_configs_for_state from pbn -> dsc target bpp_x16 bpp_x16 is calulated by compute_bpp_x16_from_target_bandwidth. Beside pixel clock and bpp, num_slices_h and bpp_increment_div will also affect bpp_x16. from dsc target bpp_x16 -> pbn within dm_update_mst_vcpi_slots_for_dsc, pbn = drm_dp_calc_pbn_mode(clock, bpp_x16, true); drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc) { return DIV_ROUND_UP_ULL(mul_u32_u32(clock * (bpp / 16), 64 * 1006), 8 * 54 * 1000 * 1000); } bpp / 16 trunc digits after decimal point. This will cause calculation delta. drm_dp_calc_pbn_mode does not have other informations, like num_slices_h, bpp_increment_div. therefore, it does not do revese calcuation properly from bpp_x16 to pbn. pbn from drm_dp_calc_pbn_mode is less than pbn from compute_mst_dsc_configs_for_state. This cause not enough mst slot allocated to display. display could not visually light up. [How] pass pbn from compute_mst_dsc_configs_for_state to dm_update_mst_vcpi_slots_for_dsc Cc: stable@xxxxxxxxxxxxxxx Reviewed-by: Scott Foster <Scott.Foster@xxxxxxx> Acked-by: Mikita Lipski <mikita.lipski@xxxxxxx> Signed-off-by: Hersen Wu <hersenwu@xxxxxxx> Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 22 ++++++++---- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 18 ++++----- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h | 11 +++++- 3 files changed, 34 insertions(+), 17 deletions(-) --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -6778,14 +6778,15 @@ const struct drm_encoder_helper_funcs am #if defined(CONFIG_DRM_AMD_DC_DCN) static int dm_update_mst_vcpi_slots_for_dsc(struct drm_atomic_state *state, - struct dc_state *dc_state) + struct dc_state *dc_state, + struct dsc_mst_fairness_vars *vars) { struct dc_stream_state *stream = NULL; struct drm_connector *connector; struct drm_connector_state *new_con_state; struct amdgpu_dm_connector *aconnector; struct dm_connector_state *dm_conn_state; - int i, j, clock, bpp; + int i, j, clock; int vcpi, pbn_div, pbn = 0; for_each_new_connector_in_state(state, connector, new_con_state, i) { @@ -6824,9 +6825,15 @@ static int dm_update_mst_vcpi_slots_for_ } pbn_div = dm_mst_get_pbn_divider(stream->link); - bpp = stream->timing.dsc_cfg.bits_per_pixel; clock = stream->timing.pix_clk_100hz / 10; - pbn = drm_dp_calc_pbn_mode(clock, bpp, true); + /* pbn is calculated by compute_mst_dsc_configs_for_state*/ + for (j = 0; j < dc_state->stream_count; j++) { + if (vars[j].aconnector == aconnector) { + pbn = vars[j].pbn; + break; + } + } + vcpi = drm_dp_mst_atomic_enable_dsc(state, aconnector->port, pbn, pbn_div, @@ -10208,6 +10215,9 @@ static int amdgpu_dm_atomic_check(struct int ret, i; bool lock_and_validation_needed = false; struct dm_crtc_state *dm_old_crtc_state; +#if defined(CONFIG_DRM_AMD_DC_DCN) + struct dsc_mst_fairness_vars vars[MAX_PIPES]; +#endif trace_amdgpu_dm_atomic_check_begin(state); @@ -10438,10 +10448,10 @@ static int amdgpu_dm_atomic_check(struct goto fail; #if defined(CONFIG_DRM_AMD_DC_DCN) - if (!compute_mst_dsc_configs_for_state(state, dm_state->context)) + if (!compute_mst_dsc_configs_for_state(state, dm_state->context, vars)) goto fail; - ret = dm_update_mst_vcpi_slots_for_dsc(state, dm_state->context); + ret = dm_update_mst_vcpi_slots_for_dsc(state, dm_state->context, vars); if (ret) goto fail; #endif --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c @@ -495,12 +495,7 @@ struct dsc_mst_fairness_params { uint32_t num_slices_h; uint32_t num_slices_v; uint32_t bpp_overwrite; -}; - -struct dsc_mst_fairness_vars { - int pbn; - bool dsc_enabled; - int bpp_x16; + struct amdgpu_dm_connector *aconnector; }; static int kbps_to_peak_pbn(int kbps) @@ -727,12 +722,12 @@ static void try_disable_dsc(struct drm_a static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state, struct dc_state *dc_state, - struct dc_link *dc_link) + struct dc_link *dc_link, + struct dsc_mst_fairness_vars *vars) { int i; struct dc_stream_state *stream; struct dsc_mst_fairness_params params[MAX_PIPES]; - struct dsc_mst_fairness_vars vars[MAX_PIPES]; struct amdgpu_dm_connector *aconnector; int count = 0; bool debugfs_overwrite = false; @@ -753,6 +748,7 @@ static bool compute_mst_dsc_configs_for_ params[count].timing = &stream->timing; params[count].sink = stream->sink; aconnector = (struct amdgpu_dm_connector *)stream->dm_stream_context; + params[count].aconnector = aconnector; params[count].port = aconnector->port; params[count].clock_force_enable = aconnector->dsc_settings.dsc_force_enable; if (params[count].clock_force_enable == DSC_CLK_FORCE_ENABLE) @@ -775,6 +771,7 @@ static bool compute_mst_dsc_configs_for_ } /* Try no compression */ for (i = 0; i < count; i++) { + vars[i].aconnector = params[i].aconnector; vars[i].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps); vars[i].dsc_enabled = false; vars[i].bpp_x16 = 0; @@ -828,7 +825,8 @@ static bool compute_mst_dsc_configs_for_ } bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state, - struct dc_state *dc_state) + struct dc_state *dc_state, + struct dsc_mst_fairness_vars *vars) { int i, j; struct dc_stream_state *stream; @@ -859,7 +857,7 @@ bool compute_mst_dsc_configs_for_state(s return false; mutex_lock(&aconnector->mst_mgr.lock); - if (!compute_mst_dsc_configs_for_link(state, dc_state, stream->link)) { + if (!compute_mst_dsc_configs_for_link(state, dc_state, stream->link, vars)) { mutex_unlock(&aconnector->mst_mgr.lock); return false; } --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h @@ -39,8 +39,17 @@ void dm_dp_create_fake_mst_encoders(struct amdgpu_device *adev); #if defined(CONFIG_DRM_AMD_DC_DCN) + +struct dsc_mst_fairness_vars { + int pbn; + bool dsc_enabled; + int bpp_x16; + struct amdgpu_dm_connector *aconnector; +}; + bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state, - struct dc_state *dc_state); + struct dc_state *dc_state, + struct dsc_mst_fairness_vars *vars); #endif #endif Patches currently in stable-queue which might be from hersenwu@xxxxxxx are queue-5.14/drm-amd-display-dsc-mst-2-4k-displays-go-dark-with-2-lane-hbr3.patch