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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4AD19C4332B for ; Mon, 23 Mar 2020 13:28:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0E99A2070A for ; Mon, 23 Mar 2020 13:28:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728385AbgCWN2Q convert rfc822-to-8bit (ORCPT ); Mon, 23 Mar 2020 09:28:16 -0400 Received: from plasma4.jpberlin.de ([80.241.57.33]:54771 "EHLO plasma4.jpberlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728344AbgCWN2Q (ORCPT ); Mon, 23 Mar 2020 09:28:16 -0400 Received: from hefe.heinlein-support.de (hefe.heinlein-support.de [91.198.250.172]) by plasma.jpberlin.de (Postfix) with ESMTP id 4FE1FBA32B; Mon, 23 Mar 2020 14:28:11 +0100 (CET) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from plasma.jpberlin.de ([91.198.250.140]) by hefe.heinlein-support.de (hefe.heinlein-support.de [91.198.250.172]) (amavisd-new, port 10030) with ESMTP id WJGZGc0gbrGQ; Mon, 23 Mar 2020 14:28:09 +0100 (CET) Received: from webmail.opensynergy.com (unknown [217.66.60.5]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (Client CN "webmail.opensynergy.com", Issuer "GeoTrust EV RSA CA 2018" (not verified)) (Authenticated sender: opensynergy@jpberlin.de) by plasma.jpberlin.de (Postfix) with ESMTPSA id 793D8BAE9C; Mon, 23 Mar 2020 14:28:09 +0100 (CET) Received: from os-lin-dmo.localnet (10.25.255.1) by MXS02.open-synergy.com (10.25.10.18) with Microsoft SMTP Server (TLS) id 14.3.487.0; Mon, 23 Mar 2020 14:28:08 +0100 From: Dmitry Sepp To: Alexandre Courbot , Keiichi Watanabe CC: Gerd Hoffmann , , Linux Media Mailing List , Alex Lau , Daniel Vetter , Dylan Reid , David Staessens , Enrico Granata , Frediano Ziglio , Hans Verkuil , =?ISO-8859-1?Q?St=E9phane?= Marchesin , Pawel Osciak , , David Stevens , Tomasz Figa , , Samiullah Khawaja , Kiran Pawar Subject: Re: [PATCH v3 1/2] virtio-video: Add virtio video device specification Date: Mon, 23 Mar 2020 14:28:08 +0100 Message-ID: <8121654.T7Z3S40VBb@os-lin-dmo> Organization: OpenSynergy In-Reply-To: References: <20200206102058.247258-1-keiichiw@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="iso-8859-1" X-Originating-IP: [10.25.255.1] Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Keiichi, On Montag, 23. März 2020 13:07:54 CET Keiichi Watanabe wrote: > Hi everyone, > > I have implemented a virtio-video device following my v3 spec in > crosvm, which worked well together with Dmitry's driver [1]. I've > started preparing v4 proposal to address problems found while > implementing the driver and the devices. Great news! > > Regarding v3 protocol, I'm thinking about how we can differentiate > 'parameters' and 'controls' in the virtio-video spec? > In the previous discussion, we decided to have a profile, level and > bitrate as controls because we want to query supported values for each > field. > But, I don't think it's a good criteria because it'd be possible to > query other values in params. Could you elaborate on this? Do you now how the design could look like or it is just an idea? AFAIR during the discussion of OpenSynergy's original v1 spec your point was to separate something that we call 'controls' now to reduce the command data size and make command handling less error prone. On one hand if don't really see any difference in params vs controls it would for sure make sense to remove one of the two. On the other hand I'd of course like to avoid moving back in forth, especially when it comes to such a major driver rework. > > So, I'm thinking about what should be the difference between params > and controls. If no difference, we should deprecate > virtio_video_params and have every field there as a control value > instead. I deem we should then deprecate controls instead. Params seem to be more abstract. Width and height don't sound like a control for me. > If we add a new command to get and set multiple controls at once, this > change won't cause overhead. > How would we do this? Provide a flexible array member where each entry has a type field first? What can also make sense is to potentially join set and get calls (probably provide 'get' stuff automatically within a response to 'set'). Anyway set and get are currently used in conjunction all the time. Best regards, Dmitry. > What do you think? Is there anything I missed? > If it sounds fine, I'll remove virtio_video_params from the v4 spec > proposal. > > Best regards, > Keiichi > > [1]: https://patchwork.linuxtv.org/patch/61717/