From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DDB873559C4; Tue, 6 Jan 2026 17:29:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767720592; cv=none; b=bnWBrycnzeVfs8vcgc5UwLcLkp95KD2i9WYy1soG/59SgadAB9mko46m0o/Xz+2DbiF3UZprxkd81jQaUXoCDeCcb3LX6ayvT7CAreGOji9rxbN8Cr+qXIFF4uzJ++9BxXRNNgVEUWK7ZpmR4QqVLdl+bPHMN8+ss/elKB1opYE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767720592; c=relaxed/simple; bh=SBoaHac52YxI+e0Zkk5ey2fgxw8D7iV77O0RgdCXFTo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=p8oJr/69d+4sk6gfgjy4Q9oh95X5vhG8HTqkC35lCU+h3+yvVmhOpSLbBK3/EgqcKZ2wV9N6Xh/p0qhQvhzfMfiu6RiDxlmRhofqbp9g+VJ1VNnQmTG0xTk3SP9ZmgR/FLhDJSkknFXErRRcbS6Of1V08b1ezFx+zMfkhKa0ZDY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0A45rBeb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0A45rBeb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1BBE1C116C6; Tue, 6 Jan 2026 17:29:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767720591; bh=SBoaHac52YxI+e0Zkk5ey2fgxw8D7iV77O0RgdCXFTo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0A45rBebjU/7Uzku+UYcJOSlCRgApVRa1W8uE6gi6RqyMR60R3+LBHOC50LE1NKuv mAffRhxOsMQtE/493c8LEaZBdpWU5Z+6vuuKIQuztJHUf5g6QjrvsGSQcA+SQoGDff 96LEPhGeFhiagErZyRQtBrl2SB5U+8FVMg0qjNAY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jerry Zuo , nat@nullable.se, Mario Limonciello , Alex Deucher Subject: [PATCH 6.12 251/567] Revert "drm/amd/display: Fix pbn to kbps Conversion" Date: Tue, 6 Jan 2026 18:00:33 +0100 Message-ID: <20260106170500.599656351@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260106170451.332875001@linuxfoundation.org> References: <20260106170451.332875001@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mario Limonciello commit 72e24456a54fe04710d89626cc5a88703e2f6202 upstream. Deeply daisy chained DP/MST displays are no longer able to light up. This reverts commit e0dec00f3d05 ("drm/amd/display: Fix pbn to kbps Conversion") Cc: Jerry Zuo Reported-by: nat@nullable.se Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4756 Signed-off-by: Mario Limonciello Acked-by: Alex Deucher Signed-off-by: Alex Deucher (cherry picked from commit e1c94109c76e8a77a21531bd53f6c63356c81158) Cc: stable@vger.kernel.org # 6.17+ Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 59 +++++++----- 1 file changed, 36 insertions(+), 23 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 @@ -846,28 +846,26 @@ struct dsc_mst_fairness_params { }; #if defined(CONFIG_DRM_AMD_DC_FP) -static uint64_t kbps_to_pbn(int kbps, bool is_peak_pbn) +static uint16_t get_fec_overhead_multiplier(struct dc_link *dc_link) { - uint64_t effective_kbps = (uint64_t)kbps; + u8 link_coding_cap; + uint16_t fec_overhead_multiplier_x1000 = PBN_FEC_OVERHEAD_MULTIPLIER_8B_10B; - if (is_peak_pbn) { // add 0.6% (1006/1000) overhead into effective kbps - effective_kbps *= 1006; - effective_kbps = div_u64(effective_kbps, 1000); - } + 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; - return (uint64_t) DIV64_U64_ROUND_UP(effective_kbps * 64, (54 * 8 * 1000)); + return fec_overhead_multiplier_x1000; } -static uint32_t pbn_to_kbps(unsigned int pbn, bool with_margin) +static int kbps_to_peak_pbn(int kbps, uint16_t fec_overhead_multiplier_x1000) { - 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; + u64 peak_kbps = kbps; - return DIV_U64_ROUND_UP(pbn_effective * 8 * 54, 64); + 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)); } static void set_dsc_configs_from_fairness_vars(struct dsc_mst_fairness_params *params, @@ -938,7 +936,7 @@ 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 = pbn_to_kbps(pbn, false); + kbps = div_u64((u64)pbn * 994 * 8 * 54, 64); dc_dsc_compute_config( param.sink->ctx->dc->res_pool->dscs[0], ¶m.sink->dsc_caps.dsc_dec_caps, @@ -967,11 +965,12 @@ 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_pbn(params[i].bw_range.max_kbps, false) - vars[i + k].pbn; + kbps_to_peak_pbn(params[i].bw_range.max_kbps, fec_overhead_multiplier_x1000) - vars[i + k].pbn; bpp_increased[i] = false; remaining_to_increase += 1; } else { @@ -1067,6 +1066,7 @@ 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_pbn(params[next_index].bw_range.stream_kbps, true); + vars[next_index].pbn = kbps_to_peak_pbn(params[next_index].bw_range.stream_kbps, fec_overhead_multiplier_x1000); ret = drm_dp_atomic_find_time_slots(state, params[next_index].port->mgr, params[next_index].port, @@ -1159,6 +1159,7 @@ 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)); @@ -1239,7 +1240,7 @@ 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_pbn(params[i].bw_range.stream_kbps, false); + vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps, fec_overhead_multiplier_x1000); 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, @@ -1261,7 +1262,7 @@ 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_pbn(params[i].bw_range.min_kbps, false); + vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.min_kbps, fec_overhead_multiplier_x1000); 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, @@ -1269,7 +1270,7 @@ static int compute_mst_dsc_configs_for_l if (ret < 0) return ret; } else { - vars[i + k].pbn = kbps_to_pbn(params[i].bw_range.stream_kbps, false); + vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps, fec_overhead_multiplier_x1000); vars[i + k].dsc_enabled = false; vars[i + k].bpp_x16 = 0; ret = drm_dp_atomic_find_time_slots(state, params[i].port->mgr, @@ -1721,6 +1722,18 @@ 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) { @@ -1812,7 +1825,7 @@ 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 = pbn_to_kbps(aconnector->mst_output_port->full_pbn, true); + virtual_channel_bw_in_kbps = kbps_from_pbn(aconnector->mst_output_port->full_pbn); /* pick the end to end bw bottleneck */ end_to_end_bw_in_kbps = min(root_link_bw_in_kbps, virtual_channel_bw_in_kbps); @@ -1863,7 +1876,7 @@ 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 = pbn_to_kbps(immediate_upstream_port->full_pbn, true); + virtual_channel_bw_in_kbps = kbps_from_pbn(immediate_upstream_port->full_pbn); 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*/