From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CAB58CA1002 for ; Tue, 2 Sep 2025 00:47:16 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6E30F10E54F; Tue, 2 Sep 2025 00:47:16 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=amd.com header.i=@amd.com header.b="h795kOVP"; dkim-atps=neutral Received: from NAM10-MW2-obe.outbound.protection.outlook.com (mail-mw2nam10on2068.outbound.protection.outlook.com [40.107.94.68]) by gabe.freedesktop.org (Postfix) with ESMTPS id 30A3010E54F for ; Tue, 2 Sep 2025 00:47:15 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=IcUjCq+yrHD0XPwh+qyFdWgXB7ckdJysAud2DtpmSXhWGNRfKYjRPIdikL+genZ2ih+V4r54ZOPwBFwSfq3aPjZccNBVZ4kH1VgAzbW9pfhe8iPqEf9OUn1HQts9/hisbvfTPmoZP9KR8woROGsPlKVHYjmWYSl1SY9nMbL2RPBGh9j20HGUa7XPYdqv0BD3H/zL3IwoXIhWMYpvnoLca50CGzjdvGTXq/vwNiN4Y/TqeBjjBf9qXzCPNXyOJ2XzlcfUgr2AKhbMnWG+2HHn31gyO6OUOAcR9gLszW73pW24Yov6vzxtA0pvGXqd4qOt5tQo/sQozlDKLxGgT/95rQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=fskpZfUEIITWNqxHXCP06DiZs+eDK9B4MgtkJO45vd4=; b=bpHR7k5k1xkjRP8s3Vk+xj4K9T721DEvG58rOSJmqI2UDK4HvIIz5CY2r+c9e7RTFpnKiEGZb1DPttUctjSZzOrEWngdVFl9/CLsgdSHRcyX/kI0rGcsTcPVZ6SZPdz9gkljXwJ6EnvXVRCmjDlaHo9J56S6C0GcphCgTRjsA3e02vKsLbXPZkGFkG7SprQ9u5mrnrmpFuUMQqwH4ZCaAuhc0Vc4aV2y7gshwXT3y4SFGyOcoz3zjp6PCQFdCuFGLHkhe6NZGjt+CCkczvOnEyZcC9KD3R7QbRxL3i9a55I666FxcRHsLtye0rPKdhCoAoxPB9BqZyrODPGqo5Vu8w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=lists.freedesktop.org smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=fskpZfUEIITWNqxHXCP06DiZs+eDK9B4MgtkJO45vd4=; b=h795kOVPOrCgt4WlU/uGvv+0IpHz6FTjA4anczSg0ERzQ2FYQlYTOYVFg8gdrJnGbgMjnZAEA4wxexhLTUhkn7U3yrmszDyinXYY795sm77+206CdyHvACza5Hghv1XjNMFeOx/4ymdkxY/0suBMnaLZ5drTA+WJvFwcFLyJE/k= Received: from CH0PR03CA0385.namprd03.prod.outlook.com (2603:10b6:610:119::20) by DM4PR12MB6182.namprd12.prod.outlook.com (2603:10b6:8:a8::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9073.24; Tue, 2 Sep 2025 00:47:09 +0000 Received: from DS2PEPF00003445.namprd04.prod.outlook.com (2603:10b6:610:119:cafe::62) by CH0PR03CA0385.outlook.office365.com (2603:10b6:610:119::20) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.9073.27 via Frontend Transport; Tue, 2 Sep 2025 00:47:09 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by DS2PEPF00003445.mail.protection.outlook.com (10.167.17.72) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.9094.14 via Frontend Transport; Tue, 2 Sep 2025 00:47:08 +0000 Received: from Satlexmb09.amd.com (10.181.42.218) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Mon, 1 Sep 2025 19:47:03 -0500 Received: from SATLEXMB04.amd.com (10.181.40.145) by satlexmb09.amd.com (10.181.42.218) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.1748.10; Mon, 1 Sep 2025 17:47:03 -0700 Received: from wayne-dev-lnx.amd.com (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server id 15.1.2507.39 via Frontend Transport; Mon, 1 Sep 2025 19:46:52 -0500 From: waynelin To: CC: Harry Wentland , Leo Li , Aurabindo Pillai , Roman Li , Wayne Lin , Tom Chung , "Fangzhi Zuo" , Dan Wheeler , Ray Wu , Ivan Lipski , Alex Hung , Fangzhi Zuo Subject: [PATCH 09/11] drm/amd/display: Fix pbn_div Calculation Error Date: Tue, 2 Sep 2025 08:42:54 +0800 Message-ID: <20250902004532.1833436-10-Wayne.Lin@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250902004532.1833436-1-Wayne.Lin@amd.com> References: <20250902004532.1833436-1-Wayne.Lin@amd.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS2PEPF00003445:EE_|DM4PR12MB6182:EE_ X-MS-Office365-Filtering-Correlation-Id: 4fcab71d-361d-4fbd-7085-08dde9ba3eec X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; ARA:13230040|36860700013|376014|1800799024|82310400026|43062017; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?a1EG1HKgUirXeuCajAUVrfOpVIhWbZXop9kFVFUtvMt/jXKZCTQCYhToP+qF?= =?us-ascii?Q?3EKVr+wfc237qYTnejDCQ+KxDy27x1aRTuX9IqBIU1WbMfVMUyA7+zKTd3Wu?= =?us-ascii?Q?Bvn2qZc+rbBqrXBThkfjwVsgelaSqIZSEYsJ1yFZctR1xIDOlUHdvKVIyiqY?= =?us-ascii?Q?CidJ+jtDgC/RqiUXiOsyuQW5U5jch+wZtimRCjivp9oyidFqnlV/KMtsfK0A?= =?us-ascii?Q?sB8hB65FFAW7+W2DSCdlPIYBVe45981nS7ibe/HjEtgANu1Y6e9sOJfz74EW?= =?us-ascii?Q?QIafc0GPHiGRMjtRGygVTho4BRAcUma4gwLX/7o+GCd752+NLQIzfvpfXiD9?= =?us-ascii?Q?luiKILuOHrU81efBdbfFbUDUpWhSz3tc0mcKiBz80CuizY+A0Map76dFbd6R?= =?us-ascii?Q?MCdWvWt7w/5TfkbiPnuX532WbF/oIx/2kYeTONf5ReNMlh/KkczTnWiNPlT+?= =?us-ascii?Q?oJKwTTvC+UPF0x3bXAIub0Vs2vJnKh7wFtZss71KFQW1Mwh0SW/6lT9vLAyz?= =?us-ascii?Q?x9S+GYZJegNDafPDTo0qUu3I+IKbAiY8jXO67Gxvw7r/c2t0lN2KE4KqQCp8?= =?us-ascii?Q?/uQxGsaVFxsw3bNRHFXEXuXvue+7yu8Hg//Nv0WBkZIz8QvMh2G5bokUKouH?= =?us-ascii?Q?e7FbyBdWKfn1dnDoGQrq8LRBdNmCGsj6YrmuKeXKb9TYp65mWiTlyPu5I1MA?= =?us-ascii?Q?r3aNn6L/arREi4zqVkyJr+BHPL77kDeHgS4oRQ/eRDgDEGxcfVJtCwHJJFiQ?= =?us-ascii?Q?H90G1jRIGsNzHdv/dCsMSs92Fl1PhajajoiU1ZwPWp4FXmsGo8H6VJnFX+u3?= =?us-ascii?Q?bDBgirnE+YMAjP97eUdBuYrRQhtzmpACm8Pydxp+r6hf0bRgslFqdjB1fTEp?= =?us-ascii?Q?4x0hGbygv/XYMe43mN7Cbht5HF/McGhH3DjQR5Hf6/8/FfDGGp5PGwDvp8Is?= =?us-ascii?Q?K1VO/mB0HrMMufsAxwpPa6G9GieYu3vHeMcw+NiFsNGmzp2bnYP4j1oVZXpx?= =?us-ascii?Q?0hxGkb9v6naCbX/qp9cwUNW6FUD5AHlp9kUteulqbKQKwK+iK/2mpQ2F+7qj?= =?us-ascii?Q?kjvmjtlS2KXa9zHy6/mFooKTFWyej5Hc2lT/iSqC9+Ad0P28kb08+H+C1sL3?= =?us-ascii?Q?AKBzhc++odEcx5gBmGIVqW0HaV2OURM4Z8cg9Xb0aZeDz+LHOua1iQ9jUEd4?= =?us-ascii?Q?YzK1IAvb1nHpa2zjXr8gvyqwJohEUEEFmKcziZVqtJ4GzR4AmLWdarXO2j75?= =?us-ascii?Q?HUhvT8vzKmpBXpmdTKg5HdaS/kHiJqiE5q3zd2YpAm2q2lk+ewFFfZ37ZcDC?= =?us-ascii?Q?xuZ1dPpWLcRr8+MLf+MnUpYLsSfqMOBa2bYucPHgW0LMkONKZ2jEVdkntF87?= =?us-ascii?Q?pGDXD78MokQYRYrRHHL4fT4WhrKQF2bNPMZUzs/az0j/05WGK/NpqYoO6xAr?= =?us-ascii?Q?zRzZJBQN+TXvKsiXp4KC8jEvrErgDwHZPnDKddcMzUFOcSbQK8plF/iTDthR?= =?us-ascii?Q?Gb0jGosWJVhFMztPcCXkwTGk9q9r9zYHqDcQKmELZu8h+4YyJcRt0JeeEg?= =?us-ascii?Q?=3D=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17; CTRY:US; LANG:en; SCL:1; SRV:; IPV:CAL; SFV:NSPM; H:SATLEXMB04.amd.com; PTR:InfoDomainNonexistent; CAT:NONE; SFS:(13230040)(36860700013)(376014)(1800799024)(82310400026)(43062017); DIR:OUT; SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Sep 2025 00:47:08.4540 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 4fcab71d-361d-4fbd-7085-08dde9ba3eec 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: DS2PEPF00003445.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB6182 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 [Why] dm_mst_get_pbn_divider() returns value integer coming from the cast from fixed point, but the casted integer will then be used in dfixed_const to be multiplied by 4096. The cast from fixed point to integer causes the calculation error becomes bigger when multiplied by 4096. That makes the calculated pbn_div value becomes smaller than it should be, which leads to the req_slot number becomes bigger. Such error is getting reflected in 8k30 timing, where the correct and incorrect calculated req_slot 62.9 Vs 63.1. That makes the wrong calculation failed to light up 8k30 after a dock under HBR3 x 4. [How] Restore the accuracy by keeping the fraction part calculated for the left shift operation. Reviewed-by: Aurabindo Pillai Signed-off-by: Fangzhi Zuo Signed-off-by: Wayne Lin --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +- .../drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 13 ++++++++++--- .../drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h | 2 +- 3 files changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index 9273bc3849f1..6a9d4545e8e7 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -8004,7 +8004,7 @@ static int dm_encoder_helper_atomic_check(struct drm_encoder *encoder, if (IS_ERR(mst_state)) return PTR_ERR(mst_state); - mst_state->pbn_div.full = dfixed_const(dm_mst_get_pbn_divider(aconnector->mst_root->dc_link)); + mst_state->pbn_div.full = dm_mst_get_pbn_divider(aconnector->mst_root->dc_link); if (!state->duplicated) { int max_bpc = conn_state->max_requested_bpc; 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 6a817508c826..2cf8f80f3764 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 @@ -853,13 +853,20 @@ void amdgpu_dm_initialize_dp_connector(struct amdgpu_display_manager *dm, drm_connector_attach_dp_subconnector_property(&aconnector->base); } -int dm_mst_get_pbn_divider(struct dc_link *link) +uint32_t dm_mst_get_pbn_divider(struct dc_link *link) { + uint32_t pbn_div_x100; + uint64_t dividend, divisor; + if (!link) return 0; - return dc_link_bandwidth_kbps(link, - dc_link_get_link_cap(link)) / (8 * 1000 * 54); + dividend = (uint64_t)dc_link_bandwidth_kbps(link, dc_link_get_link_cap(link)) * 100; + divisor = 8 * 1000 * 54; + + pbn_div_x100 = div64_u64(dividend, divisor); + + return dfixed_const(pbn_div_x100) / 100; } struct dsc_mst_fairness_params { diff --git 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 index 65f76a7d00db..6f7ea684b555 100644 --- 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 @@ -60,7 +60,7 @@ enum mst_msg_ready_type { struct amdgpu_display_manager; struct amdgpu_dm_connector; -int dm_mst_get_pbn_divider(struct dc_link *link); +uint32_t dm_mst_get_pbn_divider(struct dc_link *link); void amdgpu_dm_initialize_dp_connector(struct amdgpu_display_manager *dm, struct amdgpu_dm_connector *aconnector, -- 2.43.0