From patchwork Sun Jun 6 03:09:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Pinchart X-Patchwork-Id: 455611 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8C33EC4743E for ; Sun, 6 Jun 2021 03:09:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 67E2161429 for ; Sun, 6 Jun 2021 03:09:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230169AbhFFDLg (ORCPT ); Sat, 5 Jun 2021 23:11:36 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:52148 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230158AbhFFDLg (ORCPT ); Sat, 5 Jun 2021 23:11:36 -0400 Received: from pendragon.lan (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 5F84E3E7; Sun, 6 Jun 2021 05:09:45 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1622948985; bh=j4MzRVnm3oEXsRZghAMIVrxyMi3svD00pa9hPdI3dMo=; h=From:To:Cc:Subject:Date:From; b=doVMFdnbRwYNfXotulim82PCaaDfLBdAgdIHqYSTl3aJQ/Q5MhCXmgYKUqAWliMcD 4YbqmwZkeecntbDE+2eqOiJTyh9AHzi1DIMMQaNy9s8CaEgO5KOOdCXJy1GBV5tpDc WO11hVmpO+Rq/q1BHHM/ylBEZELr8DQFya0Ph8K0= From: Laurent Pinchart To: linux-media@vger.kernel.org Cc: Benjamin Drung , Adam Goode , stable@vger.kernel.org Subject: [PATCH v5] media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K Date: Sun, 6 Jun 2021 06:09:28 +0300 Message-Id: <20210606030928.9739-1-laurent.pinchart@ideasonboard.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org From: Benjamin Drung The Elgato Cam Link 4K HDMI video capture card reports to support three different pixel formats, where the first format depends on the connected HDMI device. ``` $ v4l2-ctl -d /dev/video0 --list-formats-ext ioctl: VIDIOC_ENUM_FMT Type: Video Capture [0]: 'NV12' (Y/CbCr 4:2:0) Size: Discrete 3840x2160 Interval: Discrete 0.033s (29.970 fps) [1]: 'NV12' (Y/CbCr 4:2:0) Size: Discrete 3840x2160 Interval: Discrete 0.033s (29.970 fps) [2]: 'YU12' (Planar YUV 4:2:0) Size: Discrete 3840x2160 Interval: Discrete 0.033s (29.970 fps) ``` Changing the pixel format to anything besides the first pixel format does not work: ``` $ v4l2-ctl -d /dev/video0 --try-fmt-video pixelformat=YU12 Format Video Capture: Width/Height : 3840/2160 Pixel Format : 'NV12' (Y/CbCr 4:2:0) Field : None Bytes per Line : 3840 Size Image : 12441600 Colorspace : sRGB Transfer Function : Rec. 709 YCbCr/HSV Encoding: Rec. 709 Quantization : Default (maps to Limited Range) Flags : ``` User space applications like VLC might show an error message on the terminal in that case: ``` libv4l2: error set_fmt gave us a different result than try_fmt! ``` Depending on the error handling of the user space applications, they might display a distorted video, because they use the wrong pixel format for decoding the stream. The Elgato Cam Link 4K responds to the USB video probe VS_PROBE_CONTROL/VS_COMMIT_CONTROL with a malformed data structure: The second byte contains bFormatIndex (instead of being the second byte of bmHint). The first byte is always zero. The third byte is always 1. The firmware bug was reported to Elgato on 2020-12-01 and it was forwarded by the support team to the developers as feature request. There is no firmware update available since then. The latest firmware for Elgato Cam Link 4K as of 2021-03-23 has MCU 20.02.19 and FPGA 67. Therefore correct the malformed data structure for this device. The change was successfully tested with VLC, OBS, and Chromium using different pixel formats (YUYV, NV12, YU12), resolutions (3840x2160, 1920x1080), and frame rates (29.970 and 59.940 fps). Cc: stable@vger.kernel.org Signed-off-by: Benjamin Drung Reviewed-by: Laurent Pinchart Signed-off-by: Laurent Pinchart --- Benjamin, could you double-check the adjustments ? I've also updated the commit messages to not mention a quirk anymore. --- drivers/media/usb/uvc/uvc_video.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index a777b389a66e..e16464606b14 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -127,10 +127,37 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit, static void uvc_fixup_video_ctrl(struct uvc_streaming *stream, struct uvc_streaming_control *ctrl) { + static const struct usb_device_id elgato_cam_link_4k = { + USB_DEVICE(0x0fd9, 0x0066) + }; struct uvc_format *format = NULL; struct uvc_frame *frame = NULL; unsigned int i; + /* + * The response of the Elgato Cam Link 4K is incorrect: The second byte + * contains bFormatIndex (instead of being the second byte of bmHint). + * The first byte is always zero. The third byte is always 1. + * + * The UVC 1.5 class specification defines the first five bits in the + * bmHint bitfield. The remaining bits are reserved and should be zero. + * Therefore a valid bmHint will be less than 32. + * + * Latest Elgato Cam Link 4K firmware as of 2021-03-23 needs this fix. + * MCU: 20.02.19, FPGA: 67 + */ + if (usb_match_one_id(stream->dev->intf, &elgato_cam_link_4k) && + ctrl->bmHint > 255) { + u8 corrected_format_index = ctrl->bmHint >> 8; + + uvc_dbg(stream->dev, VIDEO, + "Correct USB video probe response from {bmHint: 0x%04x, bFormatIndex: %u} to {bmHint: 0x%04x, bFormatIndex: %u}\n", + ctrl->bmHint, ctrl->bFormatIndex, + 1, corrected_format_index); + ctrl->bmHint = 1; + ctrl->bFormatIndex = corrected_format_index; + } + for (i = 0; i < stream->nformats; ++i) { if (stream->format[i].index == ctrl->bFormatIndex) { format = &stream->format[i];