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 ACDA0CCA470 for ; Mon, 6 Oct 2025 00:07:20 +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=evwrrorcGFo6k74yGMu33j4KuMzh6xbZ0yPvDXTUI1Y=; b=FpSKw4VegiKy9Nd23oYFOrm4eW lgaq2sjq+P4LPXlNyc3wVMfjuw6Dj//mJUX4/LjKRSl8E+u1f16ZUUoswJuI8y/B/N9lzzT69R5+a rz80+afDY/sMUFzits1gintdCHn4RAEGQhc2/J93oX1jrNA/4SfJ4x0k18UR4BWxu/5ipbQH8zlnj FkSa5SvLV2iWFWuP6ADaz9+LXSgxSPy/qgZzYKKB21YbYUwo17hK7BwMWnh8PfljKPI7KUzYFMpHH +gk10oo3Sf0+CFGQW7Dpc4OpWwyvE+KipQjZEL0j849Z8hYVeWhf4/WyQN+qAe+JM1Spbh9NM2l17 1uSnaS3w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v5Ykz-0000000GlnF-1W9j; Mon, 06 Oct 2025 00:07:13 +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 1v5Ykw-0000000Glmd-2ziy; Mon, 06 Oct 2025 00:07:11 +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 B342CC6A; Mon, 6 Oct 2025 02:05:36 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1759709136; bh=wyXL5DUf7BOraFH18XCA1euDMWfErgk4odSaPMDaCY0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cR9T5BrJCY7hA8ggq1p8fcjNLGodZD5EurkDfW8GRwSvEwZGsrm/p11uYvmLKC304 wHnwGXOzSAm1DrQec37OraoY24+a4l5lTf3E8An7uRISyW3RfsxbK8U7neDQCMUxvw ZsYkC4lKsVC4MhmKx6YbKGPAekwPVGppl7g+W5O4= Date: Mon, 6 Oct 2025 03:07:02 +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: <20251006000702.GA3305@pendragon.ideasonboard.com> References: <20250915-extensible-parameters-validation-v5-0-e6db94468af3@ideasonboard.com> <20250915-extensible-parameters-validation-v5-1-e6db94468af3@ideasonboard.com> <20251005000602.GA13055@pendragon.ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251005000602.GA13055@pendragon.ideasonboard.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251005_170710_899063_9F27A942 X-CRM114-Status: GOOD ( 48.00 ) 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 On Sun, Oct 05, 2025 at 03:06:04AM +0300, Laurent Pinchart wrote: > 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) It occurred to me that, now that this is part of v4l2-isp.h, we should probably prefer everything with v4l2_isp_. This would become V4L2_ISP_PARAMS_FL_BLOCK_DISABLE, and same for the structures below. Sorry for not noticing earlier. > > + > > +/* > > + * 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