From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 23B3A261B94; Mon, 6 Oct 2025 09:06:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759741608; cv=none; b=Hkx6FAfiy/8hHwKGZqESVWF7bCE41AKf/zikuuyDs9vyv0WVTqAHK2BzBq0BOTqoyy9xSGoKdHSWiOhMVHbFmpt2Zs5yL9kIDw+XfWxt2fB+KQ9vLCC1yijPyhStWzIxNAFsNgdZ56qMD0Zyz5QoqhBFOrJU3aMVho23C/gkm7Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759741608; c=relaxed/simple; bh=S6lA3edjtWSrrofZ3+5QYwA0fDoIiAFDiibi8xhauF8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Gt4aA4WicFM8eqUrO+EEeExszFl3zM0pp7CNAKPlTEi7wCqua3UYUgOUsfDhK8iW4hLC75Mcoro9WKNFCn2IIHsCbX/Wk9x/6qnOY4OXGlexRt47lkrBetcWHGTQEau2oW9z7dLqPQka+YU77HAjlh4v2EI54OB1RvvpfL3qMAE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=X9lEsJpG; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="X9lEsJpG" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id EBE141741; Mon, 6 Oct 2025 11:05:11 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1759741512; bh=S6lA3edjtWSrrofZ3+5QYwA0fDoIiAFDiibi8xhauF8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=X9lEsJpGi5dyPB1P6stxJfHeu93JME4jdebU1SbbhN4C4/eSj9BL2RbknGfKD6sGp scvsppWFVSVdw8Wb+PcJvkHMiO+E1CXupHqehIym0fPMUv3xkAeMjiKO8SGqn0jpwV Oea8M22Vwd0iX0Uy0DDIPxpeEr3mCMR8yOdZPgec= Date: Mon, 6 Oct 2025 12:06:37 +0300 From: Laurent Pinchart To: Dan Scally Cc: Jacopo Mondi , Dafna Hirschfeld , Keke Li , Mauro Carvalho Chehab , Heiko Stuebner , 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: <20251006090637.GA5944@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> <20251006082751.GA16422@pendragon.ideasonboard.com> <246ae834-3077-4e38-b419-5c8773139e65@ideasonboard.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <246ae834-3077-4e38-b419-5c8773139e65@ideasonboard.com> On Mon, Oct 06, 2025 at 09:46:26AM +0100, Daniel Scally wrote: > On 06/10/2025 09:27, Laurent Pinchart wrote: > > On Mon, Oct 06, 2025 at 09:15:47AM +0100, Daniel Scally wrote: > >> On 05/10/2025 01:06, Laurent Pinchart wrote: > >>> 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). > >> > >> This is because the rkisp1 and c3 ISP implementations are already merged with a custom parameters > >> buffer struct defined at [1] and [2]. There the array size is set to the max size macro. This series > >> just asserts that the header part is a size match for struct v4l2_params_buffer to guarantee > >> compatibility, so throughout those drivers they can use sizeof(struct c3_isp_params_cfg) or the > >> rkisp equivalent and it's fine. > >> > >> For new users that don't have a custom struct in their uAPI and are relying on struct > >> v4l2_params_buffer we can't just do sizeof(), so the idea was for this to provide a canonical way > >> for the size calculation to be done across both the kernel and userspace. > >> > >> If we decide that it's worth keeping but want a user in this series to justify its inclusion, it > >> could be used in patches 2 and 3 - I'll reply to patch 2 in a second to indicate where. > > > > Will it be used by userspace too for the Mali C55, or only by the kernel > > I have used it in userspace too. Any pointer to the code ? > > driver ? > > > >> [1] https://elixir.bootlin.com/linux/v6.17/source/include/uapi/linux/rkisp1-config.h#L1675 > >> [2] https://elixir.bootlin.com/linux/v6.17/source/include/uapi/linux/media/amlogic/c3-isp-config.h#L558> > >> > >>>> + > >>>> +/** > >>>> + * 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