From: Bradford Love <brad@nextdimension.cc>
Date: Tue, 17 Mar 2026 21:07:20 +0000 (-0500)
Subject: media: au0828: Fix green screen in analog
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=58119a0cffa8a597ce5d39587beb0f5a763434a0;p=thirdparty%2Fkernel%2Fstable.git

media: au0828: Fix green screen in analog

When the driver was converted to VB2 the original function to fix
green frame detection was removed and a default vb2 dqbuf function
was used instead. This vb2 dqbuf function leads to green frames not
being detected and correupting stream captures.

The vidioc_dqbuf function checks the greenscreen flag, and, if set
resets the stream to discard the green frame and decode a real frame.

Signed-off-by: Bradford Love <brad@nextdimension.cc>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
---

diff --git a/drivers/media/usb/au0828/au0828-video.c b/drivers/media/usb/au0828/au0828-video.c
index fbaa542c8259..3c53105f3d2b 100644
--- a/drivers/media/usb/au0828/au0828-video.c
+++ b/drivers/media/usb/au0828/au0828-video.c
@@ -1671,6 +1671,27 @@ static int vidioc_log_status(struct file *file, void *fh)
 	return 0;
 }
 
+static int vidioc_dqbuf(struct file *file, void *priv, struct v4l2_buffer *b)
+{
+	struct au0828_dev *dev = video_drvdata(file);
+	int rc;
+
+	rc = check_dev(dev);
+	if (rc < 0)
+		return rc;
+
+	/* Workaround for a bug in the au0828 hardware design that
+	 * sometimes results in the colorspace being inverted
+	 */
+	if (dev->greenscreen_detected == 1) {
+		dprintk(1, "Detected green frame.  Resetting stream...\n");
+		au0828_analog_stream_reset(dev);
+		dev->greenscreen_detected = 0;
+	}
+
+	return vb2_ioctl_dqbuf(file, priv, b);
+}
+
 void au0828_v4l2_suspend(struct au0828_dev *dev)
 {
 	struct urb *urb;
@@ -1764,8 +1785,8 @@ static const struct v4l2_ioctl_ops video_ioctl_ops = {
 	.vidioc_prepare_buf         = vb2_ioctl_prepare_buf,
 	.vidioc_querybuf            = vb2_ioctl_querybuf,
 	.vidioc_qbuf                = vb2_ioctl_qbuf,
-	.vidioc_dqbuf               = vb2_ioctl_dqbuf,
-	.vidioc_expbuf               = vb2_ioctl_expbuf,
+	.vidioc_dqbuf               = vidioc_dqbuf,
+	.vidioc_expbuf              = vb2_ioctl_expbuf,
 
 	.vidioc_s_std               = vidioc_s_std,
 	.vidioc_g_std               = vidioc_g_std,