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 7FBFEC021B3 for ; Thu, 20 Feb 2025 15:27:15 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1FF7D10E99D; Thu, 20 Feb 2025 15:27:15 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="WoTG9crP"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.18]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7964E10E995; Thu, 20 Feb 2025 15:27:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1740065233; x=1771601233; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=uTnLf8wvB429OSCdHA4hXdgbljgSBLn2hsDZwxYmKRU=; b=WoTG9crPQtKqLfr8m+6/4PPchRgBENV3E1M1YjiyQY3omcCi8OLBd3eV 0ButBXktoey6XtrN5qkGunDe5u325JQnG4xoehCfXTasWbJpLMvM0KtvJ uiD9s6O8rboxrOlJOgU8A7VIzJb0PrYyaVjbr14pMuty8i9vbgIopfkxN ZNLlfpGtBLz0Qy7VFQaaSR8cWhubMFE+XAveCLN4itkc1RA5Ga0VvCtAV ihxtRMH10vK86bvPMH5c8+waDni8XCKzB4dl5SrUkNpIthbt0zLiZj0/d zcARMRk3wEFJGhvYFYTiPMU4xf75OyMLtiGHqZ2MhNwEtqCuxlgzw3aec g==; X-CSE-ConnectionGUID: rSyN9k5RS66D7oT0vavQ+w== X-CSE-MsgGUID: L8D/IdRXRCWp1QVyUgeMQQ== X-IronPort-AV: E=McAfee;i="6700,10204,11314"; a="41057917" X-IronPort-AV: E=Sophos;i="6.12,310,1728975600"; d="scan'208";a="41057917" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Feb 2025 07:27:13 -0800 X-CSE-ConnectionGUID: +ZtmpS62R7KkUm/Wwx2ZoQ== X-CSE-MsgGUID: l71k36X1Qa6EQtzOn6oedQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,224,1728975600"; d="scan'208";a="120290224" Received: from stinkpipe.fi.intel.com (HELO stinkbox) ([10.237.72.74]) by orviesa005.jf.intel.com with SMTP; 20 Feb 2025 07:27:11 -0800 Received: by stinkbox (sSMTP sendmail emulation); Thu, 20 Feb 2025 17:27:10 +0200 Date: Thu, 20 Feb 2025 17:27:10 +0200 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Simona Vetter Cc: dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org Subject: Re: [PATCH] drm/atomic: Filter out redundant DPMS calls Message-ID: References: <20250219160239.17502-1-ville.syrjala@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Patchwork-Hint: comment X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Thu, Feb 20, 2025 at 11:00:28AM +0100, Simona Vetter wrote: > On Thu, Feb 20, 2025 at 10:53:57AM +0100, Simona Vetter wrote: > > On Wed, Feb 19, 2025 at 06:02:39PM +0200, Ville Syrjala wrote: > > > From: Ville Syrjälä > > > > > > Video players (eg. mpv) do periodic XResetScreenSaver() calls to > > > keep the screen on while the video playing. The modesetting ddx > > > plumbs these straight through into the kernel as DPMS setproperty > > > ioctls, without any filtering whatsoever. When implemented via > > > atomic these end up as full commits on the crtc, which leads to a > > > dropped frame every time XResetScreenSaver() is called. > > > > I think you should add here that it's just an empty commit, because we do > > filter out redundant commits where crtc->active_changed does nothing. > > Except we still run the entire machinery with timestamps and drm_event and > > everything. Yeah, it'll take at least one frame. And it's a blocking ioctl as well. > > > > And I don't think it's worth to filter that out at the atomic level, > > because it's really only legacy ioctl that had this "complete noop" > > behaviour. Yep, I think we can expect atomic userspace to do better. Oh, and you can't even set the DPMS property via the atomic uapi directly. > > > > With the commit message augmented: > > > > Reviewed-by: Simona Vetter > > Ok, one more thing: Please also augment the dpms property uapi doc text > with a note that we make this guarantee. Otherwise this feels a bit too > much opaque magic. Maybe even a one-liner comment in the code that this is > uapi? Something like this perhaps? + * On atomic drivers any DPMS setproperty ioctl where the value does not + * change is completely skipped, otherwise an atomic commit will occur. + * On legacy drivers the exact behavior is driver specific. > -Sima > > > > > Might also be nice to have a igt for this? Plus also wondering whether we > > should cc: stable it. > > > > Cheers, Sima > > > > > Let's just filter out redundant DPMS property changes in the > > > kernel to avoid this issue. > > > > > > Signed-off-by: Ville Syrjälä > > > --- > > > drivers/gpu/drm/drm_atomic_uapi.c | 4 ++++ > > > 1 file changed, 4 insertions(+) > > > > > > diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c > > > index 2765ba90ad8f..c2726af6698e 100644 > > > --- a/drivers/gpu/drm/drm_atomic_uapi.c > > > +++ b/drivers/gpu/drm/drm_atomic_uapi.c > > > @@ -957,6 +957,10 @@ int drm_atomic_connector_commit_dpms(struct drm_atomic_state *state, > > > > > > if (mode != DRM_MODE_DPMS_ON) > > > mode = DRM_MODE_DPMS_OFF; > > > + > > > + if (connector->dpms == mode) > > > + goto out; > > > + > > > connector->dpms = mode; > > > > > > crtc = connector->state->crtc; > > > -- > > > 2.45.3 > > > > > > > -- > > Simona Vetter > > Software Engineer, Intel Corporation > > http://blog.ffwll.ch > > -- > Simona Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch -- Ville Syrjälä Intel