From patchwork Sun Dec 11 13:02:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dorota Czaplejewicz X-Patchwork-Id: 13070581 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 DA7FAC001B2 for ; Sun, 11 Dec 2022 13:03:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230089AbiLKNC7 (ORCPT ); Sun, 11 Dec 2022 08:02:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51586 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229777AbiLKNC6 (ORCPT ); Sun, 11 Dec 2022 08:02:58 -0500 Received: from comms.puri.sm (comms.puri.sm [159.203.221.185]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 27DD6B494; Sun, 11 Dec 2022 05:02:55 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by comms.puri.sm (Postfix) with ESMTP id 9309CEF95D; Sun, 11 Dec 2022 05:02:54 -0800 (PST) Received: from comms.puri.sm ([127.0.0.1]) by localhost (comms.puri.sm [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id LLMKInvpj9o2; Sun, 11 Dec 2022 05:02:53 -0800 (PST) Date: Sun, 11 Dec 2022 14:02:39 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=puri.sm; s=comms; t=1670763773; bh=i0g+3oryYH+bTrIcDnrXvCPR8IHUH6ivXegwOUCTJr8=; h=Date:From:To:Subject:In-Reply-To:References:From; b=R1h3ppXnvqwH42II/jPs2ZonYRC/ueCjjTydIr5+A1IGl3KCDSKZSDLlC2qunK9Zt XLy/Po5QR46esOiiwtLbInNzJ+ATqHc7Rpf6Bw9PcHNCNT+nxPuDB8++phKpm+oWar Cn8lvBziyw5Ma+xDVkXu1rEB0pnbzZ4EsOuZrTmAyevgZBXXCegxVi8bI8SACw2fO2 0h19hqAwm7NC6o4Jn0l9Kv9YMChlRXFq7T10/sxT18YKDpt4ZlqLYrRq7u7gjzcbsN 9kaKjRmdXCtwSSC0kIhoSs3WQzZMiWIY/2yDqx7eQX4xAjCZ3qbOZ44R3T61rCDX/Q lBFtyiGCRdXJg== From: Dorota Czaplejewicz To: Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@puri.sm Subject: [PATCHv3 2/2] media api: Try to make enum usage clearer Message-ID: <20221211125718.2815126-2-dorota.czaplejewicz@puri.sm> In-Reply-To: <20221211125718.2815126-1-dorota.czaplejewicz@puri.sm> References: <20221211125718.2815126-1-dorota.czaplejewicz@puri.sm> Organization: Purism MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org This clarifies which side of the calls is responsible for doing what to which parts of the struct. It also expands the terse description of the access algorithm into more prose-like, active voice description, which trades conciseness for ease of comprehension. Fixed: typo "format" -> "frame size" in enum-frame-size Added: no holes in the enumeration Added: enumerations per what? Added: who fills in what in calls Changed: "given" -> "specified" Signed-off-by: Dorota Czaplejewicz --- .../v4l/vidioc-subdev-enum-frame-size.rst | 44 ++++++++++++------- 1 file changed, 29 insertions(+), 15 deletions(-) diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst index c25a9896df0e..82b5d2538fa9 100644 --- a/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst +++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst @@ -31,18 +31,30 @@ Arguments Description =========== -This ioctl allows applications to enumerate all frame sizes supported by -a sub-device on the given pad for the given media bus format. Supported -formats can be retrieved with the +This ioctl allows applications to access the enumeration of frame sizes +supported by a sub-device on the specified pad +for the specified media bus format. +Supported formats can be retrieved with the :ref:`VIDIOC_SUBDEV_ENUM_MBUS_CODE` ioctl. -To enumerate frame sizes applications initialize the ``pad``, ``which`` -, ``code`` and ``index`` fields of the struct -:c:type:`v4l2_subdev_mbus_code_enum` and -call the :ref:`VIDIOC_SUBDEV_ENUM_FRAME_SIZE` ioctl with a pointer to the -structure. Drivers fill the minimum and maximum frame sizes or return an -EINVAL error code if one of the input parameters is invalid. +The enumerations are defined by the driver, and indexed using the ``index`` field +of the struct :c:type:`v4l2_subdev_mbus_code_enum`. +Each pair of ``pad`` and ``code`` correspond to a separate enumeration. +Each enumeration starts with the ``index`` of 0, and +the lowest invalid index marks the end of the enumeration. + +Therefore, to enumerate frame sizes allowed on the specified pad +and using the specified mbus format, initialize the +``pad``, ``which``, and ``code`` fields to desired values, +and set ``index`` to 0. +Then call the :ref:`VIDIOC_SUBDEV_ENUM_FRAME_SIZE` ioctl with a pointer to the +structure. + +A successful call will return with minimum and maximum frame sizes filled in. +Repeat with increasing ``index`` until ``EINVAL`` is received. +``EINVAL`` means that either no more entries are available in the enumeration, +or that an input parameter was invalid. Sub-devices that only support discrete frame sizes (such as most sensors) will return one or more frame sizes with identical minimum and @@ -72,26 +84,28 @@ information about try formats. * - __u32 - ``index`` - - Number of the format in the enumeration, set by the application. + - Index of the frame size in the enumeration belonging to the given pad and format. + Filled in by the application. * - __u32 - ``pad`` - Pad number as reported by the media controller API. + Filled in by the application. * - __u32 - ``code`` - The media bus format code, as defined in - :ref:`v4l2-mbus-format`. + :ref:`v4l2-mbus-format`. Filled in by the application. * - __u32 - ``min_width`` - - Minimum frame width, in pixels. + - Minimum frame width, in pixels. Filled in by the driver. * - __u32 - ``max_width`` - - Maximum frame width, in pixels. + - Maximum frame width, in pixels. Filled in by the driver. * - __u32 - ``min_height`` - - Minimum frame height, in pixels. + - Minimum frame height, in pixels. Filled in by the driver. * - __u32 - ``max_height`` - - Maximum frame height, in pixels. + - Maximum frame height, in pixels. Filled in by the driver. * - __u32 - ``which`` - Frame sizes to be enumerated, from enum