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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 E34CCC169C4 for ; Thu, 31 Jan 2019 10:45:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C296F218AC for ; Thu, 31 Jan 2019 10:45:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727864AbfAaKpT (ORCPT ); Thu, 31 Jan 2019 05:45:19 -0500 Received: from lb1-smtp-cloud8.xs4all.net ([194.109.24.21]:37690 "EHLO lb1-smtp-cloud8.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726221AbfAaKpT (ORCPT ); Thu, 31 Jan 2019 05:45:19 -0500 Received: from [192.168.2.10] ([212.251.195.8]) by smtp-cloud8.xs4all.net with ESMTPA id p9qJgAkSQNR5yp9qNgPK9W; Thu, 31 Jan 2019 11:45:17 +0100 Subject: Re: [PATCH v3 1/2] media: docs-rst: Document memory-to-memory video decoder interface To: Tomasz Figa , linux-media@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Mauro Carvalho Chehab , Pawel Osciak , Alexandre Courbot , Kamil Debski , Andrzej Hajda , Kyungmin Park , Jeongtae Park , Philipp Zabel , =?UTF-8?B?VGlmZmFueSBMaW4gKOael+aFp+ePiik=?= , =?UTF-8?B?QW5kcmV3LUNUIENoZW4gKOmZs+aZuui/qik=?= , Stanimir Varbanov , Todor Tomov , Nicolas Dufresne , Paul Kocialkowski , Laurent Pinchart , dave.stevenson@raspberrypi.org, Ezequiel Garcia , Maxime Jourdan References: <20190124100419.26492-1-tfiga@chromium.org> <20190124100419.26492-2-tfiga@chromium.org> From: Hans Verkuil Message-ID: Date: Thu, 31 Jan 2019 11:45:11 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190124100419.26492-2-tfiga@chromium.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-CMAE-Envelope: MS4wfAP1SKWx7vj6JGa6THWk2FZ+ZO1iIWWiwOvdChXk+1pZd6gX7FLXLQz9xmaAgo4ATUdLnK7jMlJYgNO62X4PkhvaJ61jCsy/rXjEkq7oyZNZlxDawpxU /xwc5huPIdcqWumW5SaX+V/ReHhMDeg7q7maTIeVaMGdXGe6X44rv+chy6SGUH0MojIDRVY//DU2o/qNX3CW+bfqnyZvTWwqJQ48Ao0DmKoBwy2kwaoX1R2E CCgBcLqQtW8gz/cnMe/WAyXuBfzMrx6K+2gZS2twCniDJ2obLhY5Oeg8fUU/jCSq8Q1BG5F45lPREfQxFm0+4lrKEJ51sgVNZPQeaIoI/t+cbc9VDHZeNwEZ 0YwHEHHjV5TAeHk7D/oCEDAISPOBtRD1OGSDLtrr1T/0uLpjmbvgpLEniYeiy3wUMWp+DhPFhZJBSFhvaYRHD6vD9AOZfPPeSwR/9psnggKx0bMS0iRYgbFK 9Lbv2wHjDrfRHHx2FbYXAg+FueYMNKSTSKrvCrOD2GeOiuOGxxU4Mao/YIqG0by08lqzpDV1MBCSb5dZ+lJdeNUBqWzHDtv6/Tn8A4uglaZyM/2wukySbqjK RVbOdznKsj67uhhgBDjRTfDqluX7ABgM6K+mxybI4dH0GMC86eXAcJoqbKTutufKhesGVzGfa9xGP7BGFLCk6QjCA8cRYFf+TsfVPoefZbgfBIeL3LCKOJvy jd5LYUGnenwuHRAk8tKu49QBx2KVIo7ExW742+CgATCZGpT40c2OBUSDU1JTYIMmUZafGazHGVAskJJAx8RZ7stdRtg3irz779mud6GWEtbxQqfO/YEZSpjp SlLE/RQ8p/Wf2D+8t3NuqnqtrG1jRHJpNibBRYbeDcMU0c1ETMyqKPV8oL/KxXruWPMQWJ7gpAGvLO7QYjM= Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On 1/24/19 11:04 AM, Tomasz Figa wrote: > Due to complexity of the video decoding process, the V4L2 drivers of > stateful decoder hardware require specific sequences of V4L2 API calls > to be followed. These include capability enumeration, initialization, > decoding, seek, pause, dynamic resolution change, drain and end of > stream. > > Specifics of the above have been discussed during Media Workshops at > LinuxCon Europe 2012 in Barcelona and then later Embedded Linux > Conference Europe 2014 in Düsseldorf. The de facto Codec API that > originated at those events was later implemented by the drivers we already > have merged in mainline, such as s5p-mfc or coda. > > The only thing missing was the real specification included as a part of > Linux Media documentation. Fix it now and document the decoder part of > the Codec API. > > Signed-off-by: Tomasz Figa > --- > Documentation/media/uapi/v4l/dev-decoder.rst | 1076 +++++++++++++++++ > Documentation/media/uapi/v4l/dev-mem2mem.rst | 5 + > Documentation/media/uapi/v4l/pixfmt-v4l2.rst | 5 + > Documentation/media/uapi/v4l/v4l2.rst | 10 +- > .../media/uapi/v4l/vidioc-decoder-cmd.rst | 40 +- > Documentation/media/uapi/v4l/vidioc-g-fmt.rst | 14 + > 6 files changed, 1135 insertions(+), 15 deletions(-) > create mode 100644 Documentation/media/uapi/v4l/dev-decoder.rst > > +4. **This step only applies to coded formats that contain resolution information > + in the stream.** Continue queuing/dequeuing bitstream buffers to/from the > + ``OUTPUT`` queue via :c:func:`VIDIOC_QBUF` and :c:func:`VIDIOC_DQBUF`. The > + buffers will be processed and returned to the client in order, until > + required metadata to configure the ``CAPTURE`` queue are found. This is > + indicated by the decoder sending a ``V4L2_EVENT_SOURCE_CHANGE`` event with > + ``V4L2_EVENT_SRC_CH_RESOLUTION`` source change type. > + > + * It is not an error if the first buffer does not contain enough data for > + this to occur. Processing of the buffers will continue as long as more > + data is needed. > + > + * If data in a buffer that triggers the event is required to decode the > + first frame, it will not be returned to the client, until the > + initialization sequence completes and the frame is decoded. > + > + * If the client sets width and height of the ``OUTPUT`` format to 0, > + calling :c:func:`VIDIOC_G_FMT`, :c:func:`VIDIOC_S_FMT`, > + :c:func:`VIDIOC_TRY_FMT` or :c:func:`VIDIOC_REQBUFS` on the ``CAPTURE`` > + queue will return the ``-EACCES`` error code, until the decoder > + configures ``CAPTURE`` format according to stream metadata. I think this should also include the G/S_SELECTION ioctls, right? Regards, Hans