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 AE80B3FC3 for ; Sat, 11 Sep 2021 00:14:22 +0000 (UTC) Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id B2F3A510; Sat, 11 Sep 2021 02:14:20 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1631319260; bh=4UpZGtktZRzJjnFPrG8SMaKKV2PjRQ+J43145cpnXI4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=FN/h8o16ZRu/MdS33K7rxY8LPi6K8xTDkcVJnP0tKzjqcmp+1inGCm2evGXO1KhPf AwPc0jeq3/RzqiziMLzZENtju80hZGCY93+aL8HRv8HTsBGXexplSI5lKtNsozwtR+ WdZNBS5CC7LZDWCtWAAuJbzMSmWOBsuYor54oPwo= Date: Sat, 11 Sep 2021 03:13:58 +0300 From: Laurent Pinchart To: Dave Hansen Cc: Josh Triplett , Mauro Carvalho Chehab , Jonathan Corbet , ksummit@lists.linux.dev Subject: Re: [MAINTAINER SUMMIT] User-space requirements for accelerator drivers Message-ID: References: <877dfop2lx.fsf@meer.lwn.net> <20210911005214.71b55ac6@coco.lan> 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: Hi Dave, On Fri, Sep 10, 2021 at 04:48:37PM -0700, Dave Hansen wrote: > On 9/10/21 4:45 PM, Josh Triplett wrote: > > On Sat, Sep 11, 2021 at 12:52:14AM +0200, Mauro Carvalho Chehab wrote: > >> On media, enforcing userspace to always be open source would > >> have been very bad, as it would prevent several videoconferencing > >> software to exist on Linux. > > > > I don't think we should enforce that all userspace users of an interface > > be Open Source. I do think we should enforce that *some* userspace user > > of an interface be Open Source before we add the interface. > > Right, if there's *no* open userspace, we can't meaningfully test or > debug the thing. > > Maybe we don't need a whole userspace stack for every last interface, > but if folks can't even offer up a selftest, it's not a good sign. It really depends on the type of driver and device. For GPUs or camera ISPs, for instance, a selftest is pointless, a full stack is required to be able to meaningfully test the driver and use the device as those expose a very large custom API to userspace (usually in the form of command buffers that contain device-specific instructions or register values). -- Regards, Laurent Pinchart