From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (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 A46412101A7 for ; Fri, 2 Aug 2024 15:08:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722611297; cv=none; b=ip1VT1hwY/51U6iHueNQNrNr7Q0vkVi6hgSO8BAMxdM+VcsgseBKMaVHQq4KL0do4OyvM6A/7Mq2fH0aNXAjUZ9wjHI25cyPijs+uaYJqwOBN1l324Thatlh8ybVlMTer6PMH019tdik6ooSl2CL9XjlNJh9opQNW5BHG7y/jQQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722611297; c=relaxed/simple; bh=9YHLzEBPhAU5AwpROppk2stTQe7p9Sm7x8VdtUFvPA0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=m7h/eLtuqMmL0SNbr1p6zWm4LrkIKJSNfA6XbkC9Yl5dn+pygS7DCekfNDwzrO3KAKWjNzw6Z34NQ+nRqx+4hu1/LEj62X+8n65G31910bTHsd+zMXwhOs9y57BlRByQ2xzYwHeB0ptb04UW7/1y16P+xPgWjzpTULTx+lnbfP0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=wN8R0xH/; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="wN8R0xH/" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id B3F24524; Fri, 2 Aug 2024 17:07:24 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1722611244; bh=9YHLzEBPhAU5AwpROppk2stTQe7p9Sm7x8VdtUFvPA0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=wN8R0xH/4h5vT6keuaysM6cahOylGdms88O4eQlDOpVO/Gimy1l+Tq8Jf2VrH63Ve njCPmetacH0fLMeQ3Q3D9W1I15bXqzK4HesZRs+lA+EgTpi0WzXoj2DGdiX2tL+7HF CwIc3cLb04j7RGu8giXKun3HXgQB4en3xDz5lBQ0= Date: Fri, 2 Aug 2024 18:07:53 +0300 From: Laurent Pinchart To: Daniel Vetter Cc: Sakari Ailus , Ricardo Ribalda Delgado , Dan Williams , James Bottomley , ksummit@lists.linux.dev, linux-cxl@vger.kernel.org, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, jgg@nvidia.com Subject: Re: [MAINTAINERS SUMMIT] Device Passthrough Considered Harmful? Message-ID: <20240802150753.GC2725@pendragon.ideasonboard.com> References: <20240722111834.GC13497@pendragon.ideasonboard.com> <20240725200142.GF14252@pendragon.ideasonboard.com> <20240726105936.GC28621@pendragon.ideasonboard.com> <20240728171800.GJ30973@pendragon.ideasonboard.com> Precedence: bulk X-Mailing-List: ksummit@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Wed, Jul 31, 2024 at 03:15:39PM +0200, Daniel Vetter wrote: > On Wed, 31 Jul 2024 at 13:55, Sakari Ailus wrote: > > This is also very different from GPUs or accel devices that are built to be > > user-programmable. If I'd compare ISPs to different devices, then the > > closest match would probably be video codecs -- which also use V4L2. > > Really just aside, but I figured I should correct this. DRM supports > plenty of video codecs. They're all tied to gpus, but the real reason > really is that the hw has decent command submission support so that > running the entire codec in userspace except the basic memory and > batch execution and synchronization handling in the kernel is a > feasible design. And actually good, because your kernel wont ever blow > up trying to parse complex media formats because it just doesn't. I don't think V4L2 codecs parse the bitstream in the kernel either, at least not the recent ones. -- Regards, Laurent Pinchart