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 BB059E9A03B for ; Wed, 18 Feb 2026 00:46:11 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 2236D10E20A; Wed, 18 Feb 2026 00:46:11 +0000 (UTC) Received: from MTA-15-3.privateemail.com (mta-15-3.privateemail.com [198.54.122.111]) by gabe.freedesktop.org (Postfix) with ESMTPS id A8CC510E20A; Wed, 18 Feb 2026 00:46:09 +0000 (UTC) Received: from mta-15.privateemail.com (localhost [127.0.0.1]) by mta-15.privateemail.com (Postfix) with ESMTP id 4fFyVm4BDgz3hhRv; Tue, 17 Feb 2026 19:46:08 -0500 (EST) Received: from hal-station (unknown [23.129.64.147]) by mta-15.privateemail.com (Postfix) with ESMTPA; Tue, 17 Feb 2026 19:45:37 -0500 (EST) Date: Tue, 17 Feb 2026 19:45:31 -0500 From: Hamza Mahfooz To: Michel =?iso-8859-1?Q?D=E4nzer?= Cc: Mario Limonciello , dri-devel@lists.freedesktop.org, Harry Wentland , Leo Li , Rodrigo Siqueira , Alex Deucher , Christian =?iso-8859-1?Q?K=F6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Alex Hung , Wayne Lin , Aurabindo Pillai , Ivan Lipski , Timur =?iso-8859-1?Q?Krist=F3f?= , Dominik Kaszewski , amd-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/2] drm: introduce KMS recovery mechanism Message-ID: 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> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7f4a86ad-d642-444c-a576-17ff9caaa934@mailbox.org> X-Virus-Scanned: ClamAV using ClamSMTP X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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: > >> Why couldn't a full modeset? > > > > As far as I see it the only reasons why we should be timing out is > > either an interrupt went missing (perhaps due to a race condition in > > driver code) or hung hardware. In either case, the interrupt associated > > with the page flip for the current commit is long gone. > > That's a matter of bookkeeping, the interrupt isn't required to keep track of the commit and complete it. Oh, if you're talking about sending out a "fake" drm_crtc_send_vblank_event(), I had considered that. Though, drivers that have hardware vblank counters take ownership of the relevant `struct drm_pending_vblank_event` [1] pretty early on. So, there wouldn't be a way to ensure that they send that out and that would mean we never get a chance to force a full modeset. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/drm/drm_crtc.h?h=v6.19#n386 > > > >> 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).