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Wed, 30 Jul 2025 14:00:50 -0500 From: To: CC: Harry Wentland , Leo Li , Aurabindo Pillai , Roman Li , Wayne Lin , Tom Chung , "Fangzhi Zuo" , Daniel Wheeler , Ray Wu , Ivan Lipski , Alex Hung , Fangzhi Zuo , Wayne Lin Subject: [PATCH 07/12] drm/amd/display: Avoid Read Remote DPCD Many Times Date: Wed, 30 Jul 2025 14:58:58 -0400 Message-ID: <20250730185903.1023256-8-Roman.Li@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250730185903.1023256-1-Roman.Li@amd.com> References: <20250730185903.1023256-1-Roman.Li@amd.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain Received-SPF: None (SATLEXMB04.amd.com: Roman.Li@amd.com does not designate permitted sender hosts) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MN1PEPF0000F0E1:EE_|CH3PR12MB7570:EE_ X-MS-Office365-Filtering-Correlation-Id: ecc45caa-c9a4-457f-7392-08ddcf9b727b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; ARA:13230040|376014|82310400026|36860700013|1800799024; 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CTRY:US; LANG:en; SCL:1; SRV:; IPV:CAL; SFV:NSPM; H:SATLEXMB04.amd.com; PTR:InfoDomainNonexistent; CAT:NONE; SFS:(13230040)(376014)(82310400026)(36860700013)(1800799024); DIR:OUT; SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Jul 2025 19:01:10.3621 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: ecc45caa-c9a4-457f-7392-08ddcf9b727b X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d; Ip=[165.204.84.17]; Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: MN1PEPF0000F0E1.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB7570 X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" From: Fangzhi Zuo Reading remote dpcd is time consuming. Instead of reading each byte one by one, read 16 bytes together. Reviewed-by: ChiaHsuan (Tom) Chung Signed-off-by: Fangzhi Zuo Signed-off-by: Wayne Lin Signed-off-by: Roman Li --- .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git 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 index 137f18d41f1b..32281bf62f70 100644 --- 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 @@ -1763,14 +1763,17 @@ static bool dp_get_link_current_set_bw(struct drm_dp_aux *aux, uint32_t *cur_lin union lane_count_set lane_count; u8 dp_link_encoding; u8 link_bw_set = 0; + u8 data[16] = {0}; *cur_link_bw = 0; - if (drm_dp_dpcd_read(aux, DP_MAIN_LINK_CHANNEL_CODING_SET, &dp_link_encoding, 1) != 1 || - drm_dp_dpcd_read(aux, DP_LANE_COUNT_SET, &lane_count.raw, 1) != 1 || - drm_dp_dpcd_read(aux, DP_LINK_BW_SET, &link_bw_set, 1) != 1) + if (drm_dp_dpcd_read(aux, DP_LINK_BW_SET, data, 16) != 16) return false; + dp_link_encoding = data[DP_MAIN_LINK_CHANNEL_CODING_SET - DP_LINK_BW_SET]; + link_bw_set = data[DP_LINK_BW_SET - DP_LINK_BW_SET]; + lane_count.raw = data[DP_LANE_COUNT_SET - DP_LINK_BW_SET]; + switch (dp_link_encoding) { case DP_8b_10b_ENCODING: link_rate = link_bw_set; -- 2.34.1