6.12-stable review patch. If anyone has any objections, please let me know.

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From: Fangzhi Zuo Jerry.Zuo@amd.com

commit 1788ef30725da53face7e311cdf62ad65fababcd upstream.

[Why] Existing routine has two conversion sequence, pbn_to_kbps and kbps_to_pbn with margin. Non of those has without-margin calculation.

kbps_to_pbn with margin conversion includes fec overhead which has already been included in pbn_div calculation with 0.994 factor considered. It is a double counted fec overhead factor that causes potential bw loss.

[How] Add without-margin calculation. Fix fec overhead double counted issue.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3735 Reviewed-by: Aurabindo Pillai aurabindo.pillai@amd.com Signed-off-by: Fangzhi Zuo Jerry.Zuo@amd.com Signed-off-by: Ivan Lipski ivan.lipski@amd.com Tested-by: Dan Wheeler daniel.wheeler@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com (cherry picked from commit e0dec00f3d05e8c0eceaaebfdca217f8d10d380c) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 59 ++++-------- 1 file changed, 23 insertions(+), 36 deletions(-)

--- 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 @@ -846,26 +846,28 @@ struct dsc_mst_fairness_params { };

#if defined(CONFIG_DRM_AMD_DC_FP) -static uint16_t get_fec_overhead_multiplier(struct dc_link *dc_link) +static uint64_t kbps_to_pbn(int kbps, bool is_peak_pbn) { - u8 link_coding_cap; - uint16_t fec_overhead_multiplier_x1000 = PBN_FEC_OVERHEAD_MULTIPLIER_8B_10B; + uint64_t effective_kbps = (uint64_t)kbps;

- link_coding_cap = dc_link_dp_mst_decide_link_encoding_format(dc_link); - if (link_coding_cap == DP_128b_132b_ENCODING) - fec_overhead_multiplier_x1000 = PBN_FEC_OVERHEAD_MULTIPLIER_128B_132B; + if (is_peak_pbn) { // add 0.6% (1006/1000) overhead into effective kbps + effective_kbps *= 1006; + effective_kbps = div_u64(effective_kbps, 1000); + }

- return fec_overhead_multiplier_x1000; + return (uint64_t) DIV64_U64_ROUND_UP(effective_kbps * 64, (54 * 8 * 1000)); }

-static int kbps_to_peak_pbn(int kbps, uint16_t fec_overhead_multiplier_x1000) +static uint32_t pbn_to_kbps(unsigned int pbn, bool with_margin) { - u64 peak_kbps = kbps; + uint64_t pbn_effective = (uint64_t)pbn; + + if (with_margin) // deduct 0.6% (994/1000) overhead from effective pbn + pbn_effective *= (1000000 / PEAK_FACTOR_X1000); + else + pbn_effective *= 1000;

- peak_kbps *= 1006; - peak_kbps *= fec_overhead_multiplier_x1000; - peak_kbps = div_u64(peak_kbps, 1000 * 1000); - return (int) DIV64_U64_ROUND_UP(peak_kbps * 64, (54 * 8 * 1000)); + return DIV_U64_ROUND_UP(pbn_effective * 8 * 54, 64); }

static void set_dsc_configs_from_fairness_vars(struct dsc_mst_fairness_params *params, @@ -936,7 +938,7 @@ static int bpp_x16_from_pbn(struct dsc_m dc_dsc_get_default_config_option(param.sink->ctx->dc, &dsc_options); dsc_options.max_target_bpp_limit_override_x16 = drm_connector->display_info.max_dsc_bpp * 16;

- kbps = div_u64((u64)pbn * 994 * 8 * 54, 64); + kbps = pbn_to_kbps(pbn, false); dc_dsc_compute_config( param.sink->ctx->dc->res_pool->dscs[0], &param.sink->dsc_caps.dsc_dec_caps, @@ -965,12 +967,11 @@ static int increase_dsc_bpp(struct drm_a int link_timeslots_used; int fair_pbn_alloc; int ret = 0; - uint16_t fec_overhead_multiplier_x1000 = get_fec_overhead_multiplier(dc_link);

for (i = 0; i < count; i++) { if (vars[i + k].dsc_enabled) { initial_slack[i] = - kbps_to_peak_pbn(params[i].bw_range.max_kbps, fec_overhead_multiplier_x1000) - vars[i + k].pbn; + kbps_to_pbn(params[i].bw_range.max_kbps, false) - vars[i + k].pbn; bpp_increased[i] = false; remaining_to_increase += 1; } else { @@ -1066,7 +1067,6 @@ static int try_disable_dsc(struct drm_at int next_index; int remaining_to_try = 0; int ret; - uint16_t fec_overhead_multiplier_x1000 = get_fec_overhead_multiplier(dc_link); int var_pbn;

for (i = 0; i < count; i++) { @@ -1099,7 +1099,7 @@ static int try_disable_dsc(struct drm_at

DRM_DEBUG_DRIVER("MST_DSC index #%d, try no compression\n", next_index); var_pbn = vars[next_index].pbn; - vars[next_index].pbn = kbps_to_peak_pbn(params[next_index].bw_range.stream_kbps, fec_overhead_multiplier_x1000); + vars[next_index].pbn = kbps_to_pbn(params[next_index].bw_range.stream_kbps, true); ret = drm_dp_atomic_find_time_slots(state, params[next_index].port->mgr, params[next_index].port, @@ -1159,7 +1159,6 @@ static int compute_mst_dsc_configs_for_l int count = 0; int i, k, ret; bool debugfs_overwrite = false; - uint16_t fec_overhead_multiplier_x1000 = get_fec_overhead_multiplier(dc_link); struct drm_connector_state *new_conn_state;

memset(params, 0, sizeof(params)); @@ -1240,7 +1239,7 @@ static int compute_mst_dsc_configs_for_l DRM_DEBUG_DRIVER("MST_DSC Try no compression\n"); for (i = 0; i < count; i++) { vars[i + k].aconnector = params[i].aconnector; - vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps, fec_overhead_multiplier_x1000); + vars[i + k].pbn = kbps_to_pbn(params[i].bw_range.stream_kbps, false); vars[i + k].dsc_enabled = false; vars[i + k].bpp_x16 = 0; ret = drm_dp_atomic_find_time_slots(state, params[i].port->mgr, params[i].port, @@ -1262,7 +1261,7 @@ static int compute_mst_dsc_configs_for_l DRM_DEBUG_DRIVER("MST_DSC Try max compression\n"); for (i = 0; i < count; i++) { if (params[i].compression_possible && params[i].clock_force_enable != DSC_CLK_FORCE_DISABLE) { - vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.min_kbps, fec_overhead_multiplier_x1000); + vars[i + k].pbn = kbps_to_pbn(params[i].bw_range.min_kbps, false); vars[i + k].dsc_enabled = true; vars[i + k].bpp_x16 = params[i].bw_range.min_target_bpp_x16; ret = drm_dp_atomic_find_time_slots(state, params[i].port->mgr, @@ -1270,7 +1269,7 @@ static int compute_mst_dsc_configs_for_l if (ret < 0) return ret; } else { - vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps, fec_overhead_multiplier_x1000); + vars[i + k].pbn = kbps_to_pbn(params[i].bw_range.stream_kbps, false); vars[i + k].dsc_enabled = false; vars[i + k].bpp_x16 = 0; ret = drm_dp_atomic_find_time_slots(state, params[i].port->mgr, @@ -1722,18 +1721,6 @@ clean_exit: return ret; }

-static uint32_t kbps_from_pbn(unsigned int pbn) -{ - uint64_t kbps = (uint64_t)pbn; - - kbps *= (1000000 / PEAK_FACTOR_X1000); - kbps *= 8; - kbps *= 54; - kbps /= 64; - - return (uint32_t)kbps; -} - static bool is_dsc_common_config_possible(struct dc_stream_state *stream, struct dc_dsc_bw_range *bw_range) { @@ -1825,7 +1812,7 @@ enum dc_status dm_dp_mst_is_port_support dc_link_get_highest_encoding_format(stream->link)); cur_link_settings = stream->link->verified_link_cap; root_link_bw_in_kbps = dc_link_bandwidth_kbps(aconnector->dc_link, &cur_link_settings); - virtual_channel_bw_in_kbps = kbps_from_pbn(aconnector->mst_output_port->full_pbn); + virtual_channel_bw_in_kbps = pbn_to_kbps(aconnector->mst_output_port->full_pbn, true);

/* pick the end to end bw bottleneck */ end_to_end_bw_in_kbps = min(root_link_bw_in_kbps, virtual_channel_bw_in_kbps); @@ -1876,7 +1863,7 @@ enum dc_status dm_dp_mst_is_port_support immediate_upstream_port = aconnector->mst_output_port->parent->port_parent;

if (immediate_upstream_port) { - virtual_channel_bw_in_kbps = kbps_from_pbn(immediate_upstream_port->full_pbn); + virtual_channel_bw_in_kbps = pbn_to_kbps(immediate_upstream_port->full_pbn, true); virtual_channel_bw_in_kbps = min(root_link_bw_in_kbps, virtual_channel_bw_in_kbps); } else { /* For topology LCT 1 case - only one mstb*/