From 8a652a17e3c005dcdae31b6c8fdf14382a29cbbe Mon Sep 17 00:00:00 2001
From: Adam Goode <agoode@google.com>
Date: Sun, 23 Aug 2020 03:21:33 +0200
Subject: [PATCH] media: uvcvideo: Ensure all probed info is returned to v4l2
Git-commit: 8a652a17e3c005dcdae31b6c8fdf14382a29cbbe
Patch-mainline: v5.10-rc1
References: bsc#1180117

bFrameIndex and bFormatIndex can be negotiated by the camera during
probing, resulting in the camera choosing a different format than
expected. v4l2 can already accommodate such changes, but the code was
not updating the proper fields.

Without such a change, v4l2 would potentially interpret the payload
incorrectly, causing corrupted output. This was happening on the
Elgato HD60 S+, which currently always renegotiates to format 1.

As an aside, the Elgato firmware is buggy and should not be renegotating,
but it is still a valid thing for the camera to do. Both macOS and Windows
will properly probe and read uncorrupted images from this camera.

With this change, both qv4l2 and chromium can now read uncorrupted video
from the Elgato HD60 S+.

[Add blank lines, remove periods at the of messages]

Signed-off-by: Adam Goode <agoode@google.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/media/usb/uvc/uvc_v4l2.c |   30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -247,11 +247,41 @@ static int uvc_v4l2_try_format(struct uv
 	if (ret < 0)
 		goto done;
 
+	/* After the probe, update fmt with the values returned from
+	 * negotiation with the device.
+	 */
+	for (i = 0; i < stream->nformats; ++i) {
+		if (probe->bFormatIndex == stream->format[i].index) {
+			format = &stream->format[i];
+			break;
+		}
+	}
+
+	if (i == stream->nformats) {
+		uvc_trace(UVC_TRACE_FORMAT, "Unknown bFormatIndex %u\n",
+			  probe->bFormatIndex);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < format->nframes; ++i) {
+		if (probe->bFrameIndex == format->frame[i].bFrameIndex) {
+			frame = &format->frame[i];
+			break;
+		}
+	}
+
+	if (i == format->nframes) {
+		uvc_trace(UVC_TRACE_FORMAT, "Unknown bFrameIndex %u\n",
+			  probe->bFrameIndex);
+		return -EINVAL;
+	}
+
 	fmt->fmt.pix.width = frame->wWidth;
 	fmt->fmt.pix.height = frame->wHeight;
 	fmt->fmt.pix.field = V4L2_FIELD_NONE;
 	fmt->fmt.pix.bytesperline = uvc_v4l2_get_bytesperline(format, frame);
 	fmt->fmt.pix.sizeimage = probe->dwMaxVideoFrameSize;
+	fmt->fmt.pix.pixelformat = format->fcc;
 	fmt->fmt.pix.colorspace = format->colorspace;
 	fmt->fmt.pix.priv = 0;