From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-201.mailbox.org (mout-p-201.mailbox.org [80.241.56.171]) (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 18500347BC7 for ; Fri, 20 Feb 2026 14:08:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771596494; cv=none; b=T0ga5p8Y0WxXdDkO/+ufL7qhsAfjakVlnLhz70MDbi8pU2CINwVsJt2h8/HItRzKidRLMPMOQ4n0Z0aO8rdVqTL79KeD+BeUPL6eBbMZw78gpb+DFKgza/axNFejl6CUP/2hXzCXlNJ2SPWCszcvkTg7aLFpc13ib9LGsU5uAAI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771596494; c=relaxed/simple; bh=+2vUG+1QHidnHW3W3guchLi84sqCLeV1rmc7+eTro7A=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=gVEGu0/5xaCjxkFAOPe6nqR+3KY/nlW16O6XM6t62XyzTIoL8uf9GCJrLTYxUkEXAL8e5rP/tPMgnC2k6Ef1ODBBPi+UWxo8RvwWT7xYtKxbs8yFU5Ju9YRyQFeBPjQC98frPdYm0/ubzOy4zVFVNB+PipkDXN/mzAA7GcOKYVY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org; spf=pass smtp.mailfrom=mailbox.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b=QbigmygX; arc=none smtp.client-ip=80.241.56.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mailbox.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b="QbigmygX" Received: from smtp102.mailbox.org (smtp102.mailbox.org [10.196.197.102]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-201.mailbox.org (Postfix) with ESMTPS id 4fHXCD0nqJz9thB; Fri, 20 Feb 2026 15:08:08 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1771596488; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yxQwWnys7SPdXyBlDqrzT4YU31/lCrXbaFhh/RoYuFY=; b=QbigmygXDeBY5xwras81h3C3pHOwyk0U07l+YbnlZFaXK9PC52JoHea6I31WGfS2L461Jr 5bu5M9nVvzo/JpjcSCU001NgpOYZExkmEtgi3Zn2+30ag1iG1R4gmmjWHtpMgv3F9BnzG1 o070tqsgr9B2iuk6sfmpFdjUugixCeciDU8SGoMFV9J/LNhTHExjIV1Ma808VKFdCRDIrW i1R/1ieS0fifu3HaggURcsV9UkT6oWTo0WCJ3LNcsmfy4bYWZn3RsQbo9/mDqpGDJsurdC 5Rh43YB6g0Lh7OPYCWz9HJGa/Ydg40ChaXqsbbhxZeOC3kxjkV4Ed9XV8TsNUg== Message-ID: <600034fb-d7e9-4249-8a28-71ed9ed194a0@mailbox.org> Date: Fri, 20 Feb 2026 15:08:00 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v3 1/2] drm: introduce KMS recovery mechanism From: =?UTF-8?Q?Michel_D=C3=A4nzer?= To: Hamza Mahfooz Cc: Mario Limonciello , dri-devel@lists.freedesktop.org, Harry Wentland , Leo Li , Rodrigo Siqueira , Alex Deucher , =?UTF-8?Q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Alex Hung , Wayne Lin , Aurabindo Pillai , Ivan Lipski , =?UTF-8?Q?Timur_Krist=C3=B3f?= , Dominik Kaszewski , amd-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20260212230905.688006-1-someguy@effective-light.com> <2e359cd9-0192-44d0-886f-7f93a8b0a4fa@amd.com> <85319290-4027-4eb8-95d1-9009d23f2294@mailbox.org> <7f4a86ad-d642-444c-a576-17ff9caaa934@mailbox.org> <8588dcbc-621e-43db-9d69-32398f75d9e6@mailbox.org> Content-Language: de-CH-frami, en-CA In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-MBO-RS-META: 4q757zqrarzrhfxj8488zwzhqyxnb17h X-MBO-RS-ID: 882b08cac187514c1bd On 2/20/26 10:09, Michel Dänzer wrote: > On 2/20/26 09:42, Michel Dänzer wrote: >> On 2/18/26 10:22, Michel Dänzer wrote: >>> On 2/18/26 01:45, Hamza Mahfooz wrote: >>>> On Mon, Feb 16, 2026 at 10:28:13AM +0100, Michel Dänzer wrote: >>>>> On 2/14/26 23:16, Hamza Mahfooz wrote: >>>>>> On Sat, Feb 14, 2026 at 03:02:49PM +0100, Michel Dänzer wrote: >>>>>> >>>>>>> In principle it's possible to do (the equivalent of) a modeset with the current state for all CRTCs, no need to do it separately per CRTC. >>>>>> >>>>>> AFAIK that is what the uevent is already doing (unless I'm mistaken). >>>>> >>>>> This is about just doing a full modeset, which isn't something user space can do in response to a wedged event. >>>> >>>> I was referring to what compositors are doing in response to >>>> `drm_kms_helper_hotplug_event()`. Perhaps, the enum constants should be >>>> renamed, since the forced modeset is actually sent when the current >>>> reset phase is DRM_KMS_RESET_NONE (the phase is updated before sending >>>> out the event though). >>> >>> Ah, you're talking about the drm_kms_helper_hotplug_event call in drm_atomic_helper_wait_for_flip_done (I thought "uevent" referred to drm_dev_wedged_event in patch 2). >>> >>> I don't know about other compositors, but I don't think mutter will do a modeset in response to a hotplug event if no KMS state changed (because some monitors can generate spurious hotplug events). >> >> FWIW, if it really turns out impossible for the kernel to do a modeset itself (which I remain unconvinced of), one way to require a modeset from user space is to set the "link-status" connector property to "Bad". > > Having written that down, a reason why the kernel can't just do a modeset itself occurred to me: A modeset might affect other CRTCs than the ones affected by the timed-out commit, which could interact badly with other pending commits affecting those other CRTCs. > > The "link-status" property seems like the best solution so far. Discussing the "link-status" property, it turns out I slightly misremembered its purpose, it's not really suitable for this. Maybe the hotplug event is the only way after all. -- Earthling Michel Dänzer \ GNOME / Xwayland / Mesa developer https://redhat.com \ Libre software enthusiast