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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 BBF3CC433FF for ; Tue, 13 Aug 2019 14:04:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96039206C2 for ; Tue, 13 Aug 2019 14:04:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728774AbfHMOEm (ORCPT ); Tue, 13 Aug 2019 10:04:42 -0400 Received: from lb2-smtp-cloud8.xs4all.net ([194.109.24.25]:48251 "EHLO lb2-smtp-cloud8.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727724AbfHMOEm (ORCPT ); Tue, 13 Aug 2019 10:04:42 -0400 Received: from [IPv6:2001:420:44c1:2579:155e:93d7:78eb:5531] ([IPv6:2001:420:44c1:2579:155e:93d7:78eb:5531]) by smtp-cloud8.xs4all.net with ESMTPA id xXPhhM0AxqTdhxXPkhA5wv; Tue, 13 Aug 2019 16:04:40 +0200 Subject: Re: [PATCH v2 1/1] v4l: Documentation: Serial busses use parallel mbus codes To: Sakari Ailus , linux-media@vger.kernel.org References: <20190813135520.5981-1-sakari.ailus@linux.intel.com> From: Hans Verkuil Message-ID: Date: Tue, 13 Aug 2019 16:04:37 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190813135520.5981-1-sakari.ailus@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4wfIdjZFhT86mDMmzG6wt8mhWI8wVO6Xsth4vdLWPtNk8JzFE26Xn1p/H6/L9Qqb0oUavCCipRLaW9G7+voY/jaihn75+7Lq9tSVVNIDJ1pzrE3S8DPNCI d9w3WfDrRhET6dI8mOrJJVMjraccSw2LG9r13bofmJPocelE2WuG3cS5h7q+doDlR7K5uQf/CKfcPQhq6umBSv5Js+ok2PtXYbcc4RGTHxIdnQzhJMCDM9+F KTfn+W7vrehnu+riHzeCLdJQJoVi2HJW9Be94Qjv3ZikWzwVoQrdd+bKUHMZDM20GA9Ckmezf0The0n9rzDzmqt3catcgr1JE4tWF7fBfLQ= Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On 8/13/19 3:55 PM, Sakari Ailus wrote: > When the support for serial busses was introduced in V4L2, it was decided > to use the existing parallel bus media bus pixel codes to describe them. > While this was a practical choice at the time, it necessitates choosing > which one of the many parallel mbus pixel codes to use, for on the serial > busses these formats are effectively all equivalent. > > The practice has always been to use the pixel code that describes a bus > that transfers a single sample per clock. Document this. > > Signed-off-by: Sakari Ailus Acked-by: Hans Verkuil Regards, Hans > --- > since v1: > > - Add an example of mbus pixel codes on serial and parallel busses. > > Documentation/media/kapi/csi2.rst | 7 +++++++ > Documentation/media/uapi/v4l/subdev-formats.rst | 8 ++++++++ > 2 files changed, 15 insertions(+) > > diff --git a/Documentation/media/kapi/csi2.rst b/Documentation/media/kapi/csi2.rst > index a7e75e2eba85a..c67736a15c45b 100644 > --- a/Documentation/media/kapi/csi2.rst > +++ b/Documentation/media/kapi/csi2.rst > @@ -72,3 +72,10 @@ the transmitter up by using the > :c:type:`v4l2_subdev_core_ops`->s_power() callback. This may take > place either indirectly by using :c:func:`v4l2_pipeline_pm_use` or > directly. > + > +Formats > +------- > + > +The media bus pixel codes document parallel formats. Should the pixel data be > +transported over a serial bus, the media bus pixel code that describes a > +parallel format that transfers a sample on a single clock cycle is used. > diff --git a/Documentation/media/uapi/v4l/subdev-formats.rst b/Documentation/media/uapi/v4l/subdev-formats.rst > index ab1a48a5ae80b..7b8e17c7b68b4 100644 > --- a/Documentation/media/uapi/v4l/subdev-formats.rst > +++ b/Documentation/media/uapi/v4l/subdev-formats.rst > @@ -85,6 +85,14 @@ formats in memory (a raw Bayer image won't be magically converted to > JPEG just by storing it to memory), there is no one-to-one > correspondence between them. > > +The media bus pixel codes document parallel formats. Should the pixel data be > +transported over a serial bus, the media bus pixel code that describes a > +parallel format that transfers a sample on a single clock cycle is used. For > +instance, both MEDIA_BUS_FMT_BGR888_1X24 and MEDIA_BUS_FMT_BGR888_3X8 are used > +on parallel busses for transferring an 8 bits per sample BGR data, whereas on > +serial busses the data in this format is only referred to using > +MEDIA_BUS_FMT_BGR888_1X24. This is because there is effectively only a single > +way to transport that format on the serial busses. > > Packed RGB Formats > ^^^^^^^^^^^^^^^^^^ >