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 X-Spam-Level: X-Spam-Status: No, score=-15.8 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 autolearn=unavailable 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 ED9B9C4743F for ; Sat, 5 Jun 2021 20:14:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D52176120E for ; Sat, 5 Jun 2021 20:14:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230104AbhFEUQ3 (ORCPT ); Sat, 5 Jun 2021 16:16:29 -0400 Received: from mout02.posteo.de ([185.67.36.66]:47103 "EHLO mout02.posteo.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230048AbhFEUQ1 (ORCPT ); Sat, 5 Jun 2021 16:16:27 -0400 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id BE4E12400FF for ; Sat, 5 Jun 2021 22:14:37 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.de; s=2017; t=1622924077; bh=nDHCUqSUkkNBEjr1gvugejRktRvRb7DwVwnaQYqgTkI=; h=From:To:Cc:Subject:Date:From; b=EzbdNl4bd1CDjSTTyPRw3aQwEZLt2i7oCtC39gGH3nhC0n4aFea4cWsepQz99ZqgS PL7p539kxFBdzZNtHVf428jFaj338bPQNEeferqoqLq41dLg1FnzHq5ajuAo1czf/d CNQUT5qw9Q2IzUI30NKI33XiVlWtai4a1Q647USSX1GPGytZNG7v6xMVvUXngbCgpm 4xOfnGYrOzzq6f7h+S32LqQNgQYsCNQZr6N1lCN1ROx8AQhcGQEn8dyjq3ii+jySsC 8jydvYJoUGxBdRW4mJlOlFvnzDe1EGCqvAYnN6gPeb2/xNawaDC7NBT9M4PY9SUhMl n06LZhJn4S7+Q== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4Fy9pP0X9yz9rxF; Sat, 5 Jun 2021 22:14:37 +0200 (CEST) From: Benjamin Drung To: Linus Torvalds , Adam Goode , Laurent Pinchart , Mauro Carvalho Chehab Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Benjamin Drung , stable@vger.kernel.org Subject: [PATCH v3] media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K Date: Sat, 5 Jun 2021 20:13:33 +0000 Message-Id: <20210605201332.52040-1-bdrung@posteo.de> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 add a quirk to correct the malformed data structure. The quirk 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 --- drivers/media/usb/uvc/uvc_video.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) v2: enhanced the comment describing the quirk v3: * hardcode ctrl->bmHint to 1 * Use UVC_DBG_VIDEO instead of UVC_DBG_CONTROL (to match the rest of the file) v4: * Replace quirk bit by specific check for USB VID:PID test I tried setting different values for bmHint, but the response from the Cam Link was always 1. So this patch hardcodes ctrl->bmHint to 1 as suggested. Patch version 4 implements the recommendation of Laurent Pinchart. It requires defining the device ID as variable since usb_match_one_id takes an pointer to it. In case more Elgato products like Game Capture HD 60 S+ (0fd9:006a) are affected, this version is harder to extent. Take patch version 3 or 4 depending on which version you prefer. Both work and are tested. diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index a777b389a66e..35c3ce0e0716 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -130,6 +130,31 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream, struct uvc_format *format = NULL; struct uvc_frame *frame = NULL; unsigned int i; + static const struct usb_device_id elgato_cam_link_4k = { USB_DEVICE(0x0fd9, 0x0066) }; + + /* + * 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 quirk. + * 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; + + corrected_format_index = ctrl->bmHint >> 8; + uvc_dbg(stream->dev, VIDEO, + "Correct USB video probe response from {bmHint: 0x%04x, bFormatIndex: 0x%02x} to {bmHint: 0x%04x, bFormatIndex: 0x%02x}.\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) { -- 2.27.0