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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1CBBFCAC5BB for ; Sun, 5 Oct 2025 00:06:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=+LOL8uNrKaAoRgtECRIWR9hSScmL+YV/a8EcGIGo0UY=; b=V4KX5Kmd2I/fsVSF6SwHIpkYrF ORCgfeuT8Rb4JjJt8TGowS9tdZ8zmQlGUnPOzNtaTfi5DXG1M62GZeLD3KD5RP3MK7J7JI9oT3kgS ZA1c/ZsncAu2ZxSoa33DRe0s6yaIauhQgZrpuVycXG8+REpCkhZtwQng2FP8tRYxFHYl+nx9+sWOV wmpqXaHHMWRzHEhrCRws3zAzfJIyJgYbQGDx9Z8UCj/arhHIiUxIJ16LSdyr8gUYW/xDSjT1KpWra MSoVXCuNAZDf9gLTDcLwydBoo2vlrnlE9EE5xj54oJLRuYSCWfXl0Osjoes39Fcx2BXJEO3Lh0mo5 G3PkIdCg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v5CGW-0000000E7xl-453m; Sun, 05 Oct 2025 00:06:16 +0000 Received: from perceval.ideasonboard.com ([213.167.242.64]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v5CGR-0000000E7x0-3llQ; Sun, 05 Oct 2025 00:06:14 +0000 Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 9692AC6E; Sun, 5 Oct 2025 02:04:37 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1759622677; bh=B5Q2wg4gtr6QBw1ikKdwKhCnjx6yt0fT9kl9hUSqRFw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YavOJh5XUI6a68aSlH5zwyPgl7lo3tGx3BjNxd5bvA1PcUGDtamO2blAXXhdr92f3 QsMdKr3i0Nbwv6mknD/NNzS1DhcUkSJDoMwOORYamk8VpxsO3s2ALVDmzbEuc0n0m/ +yioStbjKE0QZk5zMCNmkrzFlKVgTyMmp1oaBoXE= Date: Sun, 5 Oct 2025 03:06:02 +0300 From: Laurent Pinchart To: Jacopo Mondi Cc: Dafna Hirschfeld , Keke Li , Mauro Carvalho Chehab , Heiko Stuebner , Dan Scally , Sakari Ailus , Antoine Bouyer , linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v5 1/8] media: uapi: Introduce V4L2 generic ISP types Message-ID: <20251005000602.GA13055@pendragon.ideasonboard.com> References: <20250915-extensible-parameters-validation-v5-0-e6db94468af3@ideasonboard.com> <20250915-extensible-parameters-validation-v5-1-e6db94468af3@ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250915-extensible-parameters-validation-v5-1-e6db94468af3@ideasonboard.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251004_170612_089183_2C49E4B2 X-CRM114-Status: GOOD ( 38.37 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Jacopo, Thank you for the patch. On Mon, Sep 15, 2025 at 07:18:10PM +0200, Jacopo Mondi wrote: > Introduce v4l2-isp.h in the Linux kernel uAPI. > > The header includes types for generic ISP configuration parameters > and will be extended in future with support for generic ISP statistics s/in future/in the future/ (and you can reflow the commit message) > formats. > > Generic ISP parameters support is provided by introducing two new > types that represent an extensible and versioned buffer of ISP > configuration parameters. > > The v4l2_params_block_header structure represents the header to be > prepend to each ISP configuration block and the v4l2_params_buffer type > represents the base type for the configuration parameters buffer. The second part of the sentence describes the same structure as the next paragraph. > The v4l2_params_buffer represents the container for the ISP > configuration data block. The generic type is defined with a 0-sized > data member that the ISP driver implementations shall properly size > according to their capabilities. This will be easier to understand if you describe v4l2_params_buffer first. The commit message would benefit from being rewritten. > [Add v4l2_params_buffer_size()] > Signed-off-by: Daniel Scally > Reviewed-by: Daniel Scally > Signed-off-by: Jacopo Mondi > --- > MAINTAINERS | 6 +++ > include/uapi/linux/media/v4l2-isp.h | 100 ++++++++++++++++++++++++++++++++++++ > 2 files changed, 106 insertions(+) > > diff --git a/MAINTAINERS b/MAINTAINERS > index ee8cb2db483f6a5e96b62b6f2edd05b1427b69f5..e82c3d0758d6033fe8fcd56ffde2c03c4319fd11 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -26410,6 +26410,12 @@ F: drivers/media/i2c/vd55g1.c > F: drivers/media/i2c/vd56g3.c > F: drivers/media/i2c/vgxy61.c > > +V4L2 GENERIC ISP PARAMETERS AND STATISTIC FORMATS > +M: Jacopo Mondi > +L: linux-media@vger.kernel.org > +S: Maintained > +F: include/uapi/linux/media/v4l2-isp.h > + > VF610 NAND DRIVER > M: Stefan Agner > L: linux-mtd@lists.infradead.org > diff --git a/include/uapi/linux/media/v4l2-isp.h b/include/uapi/linux/media/v4l2-isp.h > new file mode 100644 > index 0000000000000000000000000000000000000000..b838555dce2b290a14136ab09ea4d2dfdc95b26b > --- /dev/null > +++ b/include/uapi/linux/media/v4l2-isp.h > @@ -0,0 +1,100 @@ > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ > +/* > + * Video4Linux2 generic ISP parameters and statistics support > + * > + * Copyright (C) 2025 Ideas On Board Oy > + * Author: Jacopo Mondi > + */ > + > +#ifndef _UAPI_V4L2_ISP_H_ > +#define _UAPI_V4L2_ISP_H_ > + > +#include > +#include > + > +#define V4L2_PARAMS_FL_BLOCK_DISABLE (1U << 0) > +#define V4L2_PARAMS_FL_BLOCK_ENABLE (1U << 1) > + > +/* > + * Reserve the first 8 bits for V4L2_PARAMS_FL_* flag. > + * > + * Driver-specific flags should be defined as: > + * #define PLATFORM_SPECIFIC_FLAG0 ((1U << V4L2_PARAMS_FL_DRIVER_FLAGS(0)) s/PLATFORM/DRIVER/ > + * #define PLATFORM_SPECIFIC_FLAG1 ((1U << V4L2_PARAMS_FL_DRIVER_FLAGS(1)) > + */ > +#define V4L2_PARAMS_FL_DRIVER_FLAGS(n) ((n) + 8) > + > +/** > + * struct v4l2_params_block_header - V4L2 extensible parameters block header > + * > + * This structure represents the common part of all the ISP configuration > + * blocks. Each parameters block shall embed an instance of this structure type > + * as its first member, followed by the block-specific configuration data. The > + * driver inspects this common header to discern the block type and its size and > + * properly handle the block content. The last sentence is not relevant for the UAPI. > + * > + * The @type field is an ISP driver-specific value that identifies the block > + * type. The @size field specifies the size of the parameters block. > + * > + * The @flags field is a bitmask of per-block flags V4L2_PARAMS_FL_* and > + * driver-specific flags specified by the driver header. > + * > + * @type: The parameters block type (driver-specific) > + * @flags: A bitmask of block flags (driver-specific) > + * @size: Size (in bytes) of the parameters block, including this header I think the fields usually go right after the structure name, followed by the rest of the documentation. > + */ > +struct v4l2_params_block_header { > + __u16 type; > + __u16 flags; > + __u32 size; > +} __attribute__((aligned(8))); > + > +/** > + * v4l2_params_buffer_size - Calculate size of v4l2_params_buffer for a platform > + * > + * Users of the v4l2 extensible parameters will have differing sized data arrays > + * depending on their specific parameter buffers. Drivers and userspace will > + * need to be able to calculate the appropriate size of the struct to > + * accommodate all ISP configuration blocks provided by the platform. > + * This macro provides a convenient tool for the calculation. > + * > + * @max_params_size: The total size of the ISP configuration blocks > + */ > +#define v4l2_params_buffer_size(max_params_size) \ > + (offsetof(struct v4l2_params_buffer, data) + (max_params_size)) This isn't used in this series as far as I can tell, and neither is it used in your libcamera implementation. I'd drop the macro (as well as the mention in the commit message). > + > +/** > + * struct v4l2_params_buffer - V4L2 extensible parameters configuration > + * > + * This struct contains the configuration parameters of the ISP algorithms, s/struct/structure/ > + * serialized by userspace into a data buffer. Each configuration parameter > + * block is represented by a block-specific structure which contains a > + * :c:type:`v4l2_params_block_header` entry as first member. Userspace populates > + * the @data buffer with configuration parameters for the blocks that it intends > + * to configure. As a consequence, the data buffer effective size changes > + * according to the number of ISP blocks that userspace intends to configure and > + * is set by userspace in the @data_size field. > + * > + * The parameters buffer is versioned by the @version field to allow modifying > + * and extending its definition. Userspace shall populate the @version field to > + * inform the driver about the version it intends to use. The driver will parse > + * and handle the @data buffer according to the data layout specific to the > + * indicated version and return an error if the desired version is not > + * supported. > + * > + * For each ISP block that userspace wants to configure, a block-specific > + * structure is appended to the @data buffer, one after the other without gaps > + * in between nor overlaps. Userspace shall populate the @data_size field with I think you can drop "nor overlaps", nobody in their right mind should think the blocks could be overlayed :-) > + * the effective size, in bytes, of the @data buffer. > + * > + * @version: The parameters buffer version (driver-specific) > + * @data_size: The configuration data effective size, excluding this header > + * @data: The configuration data Move the fields up just after the structure name. Reviewed-by: Laurent Pinchart > + */ > +struct v4l2_params_buffer { > + __u32 version; > + __u32 data_size; > + __u8 data[] __counted_by(data_size); > +}; > + > +#endif /* _UAPI_V4L2_ISP_H_ */ -- Regards, Laurent Pinchart