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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F42FCA0FFA for ; Tue, 5 Sep 2023 18:11:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238294AbjIESL3 (ORCPT ); Tue, 5 Sep 2023 14:11:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239315AbjIESHm (ORCPT ); Tue, 5 Sep 2023 14:07:42 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C249E1E8F7 for ; Tue, 5 Sep 2023 10:23:52 -0700 (PDT) Received: from pendragon.ideasonboard.com (ftip006315900.acc1.colindale.21cn-nte.bt.net [81.134.214.249]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 557D7D8B; Tue, 5 Sep 2023 18:45:41 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1693932341; bh=bChNDkKa4a+ObEinooP2i2uBJXCAvSjfDakubWHx6gA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LjWsG/D3DLDlHFx4rdXHzRNH9v7Q5qBXH472DgUhA/e8a6V2aDVza37EywDiDAfCH bcffCcTn58kFAPj+atnuu0sL4dMDX2TxMGJBuKqpAc/SyIc4T3eQyzXr9XLv3nETkd cBTUwByi1mql1pBzPOqwsegG5zoOc1O6Aj8Jd2kI= Date: Tue, 5 Sep 2023 19:47:20 +0300 From: Laurent Pinchart To: Sakari Ailus Cc: Jacopo Mondi , Hans Verkuil , linux-media@vger.kernel.org, tomi.valkeinen@ideasonboard.com, bingbu.cao@intel.com, hongju.wang@intel.com, Andrey Konovalov , Dmitry Perchanov Subject: Re: [PATCH v3 07/10] media: uapi: Add generic 8-bit metadata format definitions Message-ID: <20230905164720.GC7971@pendragon.ideasonboard.com> References: <20230808075538.3043934-1-sakari.ailus@linux.intel.com> <20230808075538.3043934-8-sakari.ailus@linux.intel.com> <9d3f512c-69c6-3789-83af-d151acd58ebe@xs4all.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Sakari, On Fri, Aug 11, 2023 at 09:11:39AM +0000, Sakari Ailus wrote: > On Fri, Aug 11, 2023 at 08:31:16AM +0200, Jacopo Mondi wrote: > > > > +V4L2_META_FMT_GENERIC_CSI2_10 > > > > +----------------------------- > > > > + > > > > +V4L2_META_FMT_GENERIC_CSI2_10 contains packed 8-bit generic metadata, 10 bits > > > > +for each 8 bits of data. Every four bytes of metadata is followed by a single > > > > +byte of padding. The way the data is stored follows the CSI-2 specification. > > > > + > > > > +This format is also used on CSI-2 on 20 bits per sample format that packs two > > > > +bytes of metadata into one sample. > > > > + > > > > +This format is little endian. > > > > + > > > > +**Byte Order Of V4L2_META_FMT_GENERIC_CSI2_10.** > > > > +Each cell is one byte. "M" denotes a byte of metadata and "p" a byte of padding. > > > > > > I think you should document whether the padding is always 0 or can be any value. > > > Perhaps 'X' is a better 'name' for the padding byte in the latter case. > > > > Did I get this right that this format is supposed to work as the RAW10 > > CSI-2 packed image format, where 4 bytes contain the higher 8 bits of > > the 10 bits sample and the 5th byte every 4 contains the lower 2 bits of > > the previous 4 sample ? > > > > If that's the case, is 'padding' the correct term here ? > > What else would you call it? It'll be zeros that exist just due to the bit > depth used and as such not interesting at all. It's actually not 0, CCS requires the padding bytes to be 0x55. I wonder if the conformance test suite tests the contents of the padding bytes. -- Regards, Laurent Pinchart