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 D9DC8CD4F3C for ; Mon, 18 May 2026 13:01:48 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 77F5E10E2FF; Mon, 18 May 2026 13:01:48 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="l73z4DeQ"; dkim-atps=neutral Received: from mail-oa1-f45.google.com (mail-oa1-f45.google.com [209.85.160.45]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5278D10E6F6 for ; Mon, 18 May 2026 08:08:49 +0000 (UTC) Received: by mail-oa1-f45.google.com with SMTP id 586e51a60fabf-4042fe53946so706665fac.3 for ; Mon, 18 May 2026 01:08:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779091728; x=1779696528; darn=lists.freedesktop.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=+QLmDk5oLv8YlQxU58cLUijUUkaHidAoC22pfi4gEsY=; b=l73z4DeQgESN4Q54BEO4YFJMfG63zacncp7RtD6d9w7ekHWkAULVkUNUlQ2B17/gHJ vwcXm8uhh07rvA5ZOx0Jauiyw2se67kH+VO6VL+gSkqEbYCZyByC9TQEH81hQaFZR5ex HVnXGS0qT/6Qy185XvV2zrD5CVJg5Zo5FKCgIwwJEztGbsUYN/Foi/zUwBxlNlwlVSXI J6rj+GeDLhFn1aCOfOTtUw8vu7WgTLVkHvHmaLtDFoPVgYHR9F+iQJmXcetbcgyNHEWm FpeOJhrNKIkmXroDOjiVzTcJ8tIUzFttnOGQiduPO8E0kutnU4Zxe2U60gfu0X+h8xaQ 31fQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779091728; x=1779696528; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=+QLmDk5oLv8YlQxU58cLUijUUkaHidAoC22pfi4gEsY=; b=Xy1oDl3m4lV/W/aDWaML284CKozpZTz8wNWb7V2cRacK/xpflILAjUEx9eUcxjxvBj dFj+sp9CI5h7I2Rx+PxXK1BogZdYJvHrwsttncvpkYkrufj0ICOHr8WKm17sUMms8CHv S6cL1wZ45e2IGmxeD/6CycDQKP81ysq5y34gpit1kalQU/e/7xtUpRV/D/X8MgrAoMzm rcnM9TD5qk/FTGRHUNsm+uLniuHxmZoGOiLMqpyDGCB/xTjsV6t/J5QyrAne5SVNzF+a rBIzWaAeImIa1Bvm2ltUOPGA+rWt3T/9MszoG6ThIAx5LmbNqD5Z1NtFHk3+9Odby8uc Fqsg== X-Gm-Message-State: AOJu0YxbxQZQZbhJsyIughrtH1MQqtXv0FlVxXLuxCZ2gBVYi0u3qiNf XjpT9SeoefsYUpdVrTfIj27NIX52jBmCTGHngxW7z98Ha0dHOqMFlex0 X-Gm-Gg: Acq92OHJs0/FHD6IwBRHyD9vwJT3VjOsPqCb2nMbzGe9qbjG8tfpYAmN6ct1b2HnQjw FMNyFIegO5NJsmjKbDlHrGCfGDvcQ/kEKrhn00mUUI2ZvEWbf6lJWM4R/66R85w7XLnkb3ZEuon 6wLx4s1Y6EGR+8e01oWA9/kh2jiNf0/VBwtbUC8VhvJ8WyE36o3HsLxDIPSP4lzzq3IqeJkeaza ZrCw8dULw63H7OLROsyuJGLWcjMTLNAQVvX5Nq/X9IfinzKPBhsfD9wT3Ad1yulVJFfV4GTg1gV 0hjT7ZKLlZ+qh8HcJSGen5j/szMtyqp6AS3VZTqxSZ5sDN8A5eHc7z+7A0wuMUslXsQrPVHovFj +Bg1DwbNZEJ83jJi84XIlLW9H3M2NRkeVfb+RV7V71wMNqgV8qiQn0qPZLSWhDZGOk9xCfqkcJw 3sGmdrLRI8PYBer0A= X-Received: by 2002:a05:6871:b21:b0:42f:cd67:2b84 with SMTP id 586e51a60fabf-43a2d9cb7damr8743171fac.9.1779091728336; Mon, 18 May 2026 01:08:48 -0700 (PDT) Received: from houminxi ([72.244.37.221]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-43a957b84fdsm3602215fac.18.2026.05.18.01.08.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 May 2026 01:08:46 -0700 (PDT) From: Minxi Hou To: jwollrath@web.de Cc: amd-gfx@lists.freedesktop.org, Minxi Hou Subject: Re: 7.0-rc4 dcn31_program_compbuf_size trace Date: Mon, 18 May 2026 16:08:35 +0800 Message-ID: <20260518080835.100682-1-houminxi@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260316094232.6bb6f0bf@schienar> References: <20260316094232.6bb6f0bf@schienar> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Mailman-Approved-At: Mon, 18 May 2026 13:01:46 +0000 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" On Mon, 16 Mar 2026 09:42:32 +0100, Julian Wollrath wrote: > when turning the display off via 'xset dpms force off' I observe the > following warning and trace under 7.0-rc4 with a AMD Ryzen 7 PRO 8840U I can reproduce the same warning on different hardware with a different trigger. Machine: HP Z66 G6 14 (ProBook 4 G1ah), AMD Ryzen 7 H 255 (HawkPoint1), kernel 7.0.8-200.fc44.x86_64. Trigger: HDMI hotplug with an external 4K monitor. The Z66's HDMI port uses a DP-to-HDMI protocol converter with FRL support (dmesg shows "DP-HDMI FRL PCON supported"). Connecting the monitor at boot causes the first timeout during initialization; subsequent hotplug events repeat it at runtime. The call trace matches yours exactly: dcn31_program_compbuf_size line:141 dcn20_optimize_bandwidth dc_commit_state_no_check dc_commit_streams amdgpu_dm_atomic_commit_tail Not seen with 6.19.x. CachyOS community bisected this to: commit 592c5b80110d5e9e50873b5364818cb6f401e26d "drm/amd/display: Migrate HUBBUB register access from hwseq to hubbub component" One thing I noticed on my setup: the amdgpu driver defaults to max_bpc=16 for the HDMI connector. With a HDMI 2.0 monitor (BenQ EL2870U, Max TMDS 340 MHz) at 4K@60Hz, the higher color depth increases bandwidth demand during compbuf reprogramming and makes the timeout happen more often. Adding amdgpu.deep_color=0 helps but does not fix the root cause. Partial workaround: amdgpu.runpm=0 amdgpu.gfx_off=0 amdgpu.deep_color=0 A patch proposed by Giuseppe Ranieri in the CachyOS issue tracker [1] changes the REG_WAIT parameters from 1us*100 to 1000us*30 and resolves the warning for several users with DCN 3.1 hardware. Discussion there is ongoing about whether 2-10us*1000 would be a better fit. [1] https://github.com/CachyOS/linux-cachyos/issues/810 Minxi Hou