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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 397DDC282DA for ; Wed, 17 Apr 2019 17:21:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 071BE20821 for ; Wed, 17 Apr 2019 17:21:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733066AbfDQRVZ (ORCPT ); Wed, 17 Apr 2019 13:21:25 -0400 Received: from relay12.mail.gandi.net ([217.70.178.232]:35789 "EHLO relay12.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732746AbfDQRVX (ORCPT ); Wed, 17 Apr 2019 13:21:23 -0400 Received: from collins (196.109.29.93.rev.sfr.net [93.29.109.196]) (Authenticated sender: paul.kocialkowski@bootlin.com) by relay12.mail.gandi.net (Postfix) with ESMTPSA id 1D15A20000D; Wed, 17 Apr 2019 17:21:19 +0000 (UTC) Message-ID: <943166ee9799daf50615b1148f3f855aa90e9c84.camel@bootlin.com> Subject: Re: [PATCH v4] media: docs-rst: Document m2m stateless video decoder interface From: Paul Kocialkowski To: Nicolas Dufresne , Alexandre Courbot , Tomasz Figa , Maxime Ripard , Hans Verkuil , Dafna Hirschfeld , Mauro Carvalho Chehab , linux-media@vger.kernel.org Cc: linux-kernel@vger.kernel.org Date: Wed, 17 Apr 2019 19:21:19 +0200 In-Reply-To: References: <20190306080019.159676-1-acourbot@chromium.org> <371df0e4ec9e38d83d11171cbd98f19954cbf787.camel@ndufresne.ca> <439b7f57aa3ba2b2ed5b043f961ef87cb83912af.camel@ndufresne.ca> <59e23c5ca5bfbadf9441ea06da2e9b9b5898c6d7.camel@bootlin.com> <0b495143bb260cf9f8927ee541e7f001842ac5c3.camel@ndufresne.ca> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.32.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Le mercredi 17 avril 2019 à 12:17 -0400, Nicolas Dufresne a écrit : > In general, we say stateless from a HW point of view. It simply means > that the HW (the accelerator) can be multiplexed to process several > independent streams. While with stateful firmware, you generally can't > save the state, and ends up with a specific number of concurrent stream > (scheduling happens in the firmware). There is exception to that of > course, the newest Amlogic/Meson video decoder allow for saving the > decoder state. The registers are undocumented, since they are filled by > the HW parser, but it's separated in a way that we could multiplex. That's a nice summary! I think it constitutes a good definition of what we should call a stateless decoder. Perhaps we could write it down in the spec somewhere? > Of course we do have a state in our drivers. Each time you open an m2m > device, you create an new instance which will keep track of done jobs, > pending jobs, active format, allocated memory, etc. Yes, definitely. Cheers, Paul