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 65035310645 for ; Tue, 14 Apr 2026 18:09:50 +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=1776190191; cv=none; b=mQUQTwoMhmM8OAwOOPbKFsN9wCB385x6X1FWubZiZkocTmQdS0bN5PMlIu4Q0+4lcHs5NTkmoNBZ4mH76Oxp9HylKLRUzKoQSJZLooiPsh26JTFI/M+VAqcBhWHbaxM9a7AcAhgp7/lEIHtPz3Qpp4D6DZPUlXL2VVJOXI17pdc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776190191; c=relaxed/simple; bh=mmnwV9+d2a04HZVp+TJmC1RODyLEP9dl/mGZDXSVfwA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uvHm/kp18/ArM3eclP3S6AhAMC2yYkgMtefps8wCYLW3JZ1ftFgY5FE9NsgvBep+kMSyuuiK8dSy5q1rZNWHvLjTU4xtcwFasNsjAg3vXXvExaDc1EL3SVGtZ/TDUtXFAml3nnl+BudLlLsEllzXJbzU9WdG/xmrm/6EptslqLY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (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=kYKRxcLO; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (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="kYKRxcLO" Received: from killaraus.ideasonboard.com (2001-14ba-703d-e500--2a1.rev.dnainternet.fi [IPv6:2001:14ba:703d:e500::2a1]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 8488F1849; Tue, 14 Apr 2026 20:08:14 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1776190094; bh=mmnwV9+d2a04HZVp+TJmC1RODyLEP9dl/mGZDXSVfwA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kYKRxcLOhEVhWYTC7EtIKO1qiEmu8QyDAWPUyG58w5CPg+7KFt/9u1ZgzLz3oiLKV 2cBPh04t8ivjL2RUTQI2OoQER19C1fS/yB1bjYBW4d8GllSfbXnSEPsAfU/UlR8Ls3 Zl7bSOERKW45wO1vsUjEXa6weCoV0s7xPhxvNPU8= Date: Tue, 14 Apr 2026 21:09:45 +0300 From: Laurent Pinchart To: Nicolas Dufresne Cc: Loic Poulain , Michael Riesch , Ricardo Ribalda , Hans Verkuil , Linux Media Mailing List , Mauro Carvalho Chehab , Sean Young , Sakari Ailus , Jacopo Mondi , Niklas =?utf-8?Q?S=C3=B6derlund?= , Tomi Valkeinen , Alain Volmat , Bryan O'Donoghue , Dave Stevenson , Daniel Almeida , Michael Tretter , Tomasz Figa , Steve Cho , Kieran Bingham , Kevin Hilman , Paul Kocialkowski , Benjamin Mugnier , Hans de Goede , Maxime Ripard , Brandon Brnich , Marco Felsch , Sven =?utf-8?Q?P=C3=BCschel?= , Devarsh Thakkar , Yemike Abhilash Chandra , Jackson Lee , Jai Luthra , Mehdi Djait , "Padhi, Beleswar" , "Donadkar, Rishikesh" , Rouven Czerwinski Subject: Re: [ANNv4] Media Summit on May 26th in Nice, France Message-ID: <20260414180945.GL4061@killaraus.ideasonboard.com> References: <20260413201907.GD4034@killaraus.ideasonboard.com> <20260413211602.GE4034@killaraus.ideasonboard.com> <420e20b3-4264-4ab0-bb50-1ae60f6c837a@collabora.com> <20260414074230.GB4061@killaraus.ideasonboard.com> <20260414084259.GC4061@killaraus.ideasonboard.com> <6e4f376fd3d1624a502cb6634e0f855af7d223f5.camel@collabora.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6e4f376fd3d1624a502cb6634e0f855af7d223f5.camel@collabora.com> On Tue, Apr 14, 2026 at 01:55:20PM -0400, Nicolas Dufresne wrote: > Hey, > > Le mardi 14 avril 2026 à 11:42 +0300, Laurent Pinchart a écrit : > > Let's not reproduce the design mistakes made in the V4L2 M2M framework. > > > > I also think you need to decouple the context handling and scheduling in > > two separate components. They need to work together, but shouldn't be > > bundled into a monolithic system. Very importantly, a driver should be > > able to implement contexts with the multi-context helpers, and implement > > custom scheduling itself. > > Note that the v4l2_m2m_dev is juts miss-named, it does not wrap a specific dev > instance anymore. I'll rename and clean that up eventually, but I agree its not > meant for your purpose, and it will be a good fight to use. Its already a pretty > big miss-fit for stateful codec, which don't really have the notion of "active > central job". Jacopo's proposal is to have multi-context MC (as you already > know), making the media device as the central source of context, so I think > that's a path in the right direction. > > But I'll be honest, I would see a future where we actually drop (or break down > into pieces) VB2, which is I read you well, its not miss-aligned with your say. I won't object :-) vb2 was designed as a midlayer, and that causes headaches (I'm thinking in particular about how .start_streaming() is delayed until buffers get queued). I have less issues with vb2 than with the M2M midlayer, as vb2 gets less in the way, but I think we should overall favour for new developments smaller helpers that drivers can assemble based on their needs over monolithic midlayers. -- Regards, Laurent Pinchart