diff --git a/drivers/media/video/pwc/pwc-ctrl.c b/drivers/media/video/pwc/pwc-ctrl.c
index 6b8fbddc0747654ff197e38f25343089699b641c..1593f8deb8105e18bc9fd1d5b09e5c8b8e9f68ea 100644
--- a/drivers/media/video/pwc/pwc-ctrl.c
+++ b/drivers/media/video/pwc/pwc-ctrl.c
@@ -1386,11 +1386,16 @@ long pwc_ioctl(struct pwc_device *pdev, unsigned int cmd, void *arg)
 	{
 		ARG_DEF(int, qual)
 
+		if (pdev->iso_init) {
+			ret = -EBUSY;
+			break;
+		}
+
 		ARG_IN(qual)
 		if (ARGR(qual) < 0 || ARGR(qual) > 3)
 			ret = -EINVAL;
 		else
-			ret = pwc_try_video_mode(pdev, pdev->view.x, pdev->view.y, pdev->vframes, ARGR(qual), pdev->vsnapshot);
+			ret = pwc_set_video_mode(pdev, pdev->view.x, pdev->view.y, pdev->vframes, ARGR(qual), pdev->vsnapshot);
 		if (ret >= 0)
 			pdev->vcompression = ARGR(qual);
 		break;
diff --git a/drivers/media/video/pwc/pwc-if.c b/drivers/media/video/pwc/pwc-if.c
index b821065e387057358c3e08965186f05472e5551d..6f8b682b9245ac143022c0d8e9403f165efb26fd 100644
--- a/drivers/media/video/pwc/pwc-if.c
+++ b/drivers/media/video/pwc/pwc-if.c
@@ -966,36 +966,6 @@ void pwc_isoc_cleanup(struct pwc_device *pdev)
 	PWC_DEBUG_OPEN("<< pwc_isoc_cleanup()\n");
 }
 
-int pwc_try_video_mode(struct pwc_device *pdev, int width, int height, int new_fps, int new_compression, int new_snapshot)
-{
-	int ret, start;
-
-	/* Stop isoc stuff */
-	pwc_isoc_cleanup(pdev);
-	/* Reset parameters */
-	pwc_reset_buffers(pdev);
-	/* Try to set video mode... */
-	start = ret = pwc_set_video_mode(pdev, width, height, new_fps, new_compression, new_snapshot);
-	if (ret) {
-		PWC_DEBUG_FLOW("pwc_set_video_mode attempt 1 failed.\n");
-		/* That failed... restore old mode (we know that worked) */
-		start = pwc_set_video_mode(pdev, pdev->view.x, pdev->view.y, pdev->vframes, pdev->vcompression, pdev->vsnapshot);
-		if (start) {
-			PWC_DEBUG_FLOW("pwc_set_video_mode attempt 2 failed.\n");
-		}
-	}
-	if (start == 0)
-	{
-		if (pwc_isoc_init(pdev) < 0)
-		{
-			PWC_WARNING("Failed to restart ISOC transfers in pwc_try_video_mode.\n");
-			ret = -EAGAIN; /* let's try again, who knows if it works a second time */
-		}
-	}
-	pdev->drop_frames++; /* try to avoid garbage during switch */
-	return ret; /* Return original error code */
-}
-
 /*********
  * sysfs
  *********/
@@ -1175,7 +1145,7 @@ static int pwc_video_open(struct file *file)
 	/* Set some defaults */
 	pdev->vsnapshot = 0;
 
-	/* Start iso pipe for video; first try the last used video size
+	/* Set video size, first try the last used video size
 	   (or the default one); if that fails try QCIF/10 or QSIF/10;
 	   it that fails too, give up.
 	 */
@@ -1202,15 +1172,6 @@ static int pwc_video_open(struct file *file)
 		return i;
 	}
 
-	i = pwc_isoc_init(pdev);
-	if (i) {
-		PWC_DEBUG_OPEN("Failed to init ISOC stuff = %d.\n", i);
-		pwc_isoc_cleanup(pdev);
-		pwc_free_buffers(pdev);
-		mutex_unlock(&pdev->modlock);
-		return i;
-	}
-
 	/* Initialize the webcam to sane value */
 	pwc_set_brightness(pdev, 0x7fff);
 	pwc_set_agc(pdev, 1, 0);
@@ -1325,6 +1286,11 @@ static ssize_t pwc_video_read(struct file *file, char __user *buf,
 		goto err_out;
 	}
 
+	/* Start the stream (if not already started) */
+	rv = pwc_isoc_init(pdev);
+	if (rv)
+		goto err_out;
+
 	/* In case we're doing partial reads, we don't have to wait for a frame */
 	if (pdev->image_read_pos == 0) {
 		/* Do wait queueing according to the (doc)book */
@@ -1394,6 +1360,7 @@ static unsigned int pwc_video_poll(struct file *file, poll_table *wait)
 {
 	struct video_device *vdev = file->private_data;
 	struct pwc_device *pdev;
+	int ret;
 
 	if (vdev == NULL)
 		return -EFAULT;
@@ -1401,6 +1368,13 @@ static unsigned int pwc_video_poll(struct file *file, poll_table *wait)
 	if (pdev == NULL)
 		return -EFAULT;
 
+	/* Start the stream (if not already started) */
+	mutex_lock(&pdev->modlock);
+	ret = pwc_isoc_init(pdev);
+	mutex_unlock(&pdev->modlock);
+	if (ret)
+		return ret;
+
 	poll_wait(file, &pdev->frameq, wait);
 	if (pdev->error_status)
 		return POLLERR;
diff --git a/drivers/media/video/pwc/pwc-v4l.c b/drivers/media/video/pwc/pwc-v4l.c
index 7061a03f5cf1de8a2df38d8632ef6c57084c4cd6..2ef1668638f9694e2b28e0a4d7cb3adcc4f1d6fb 100644
--- a/drivers/media/video/pwc/pwc-v4l.c
+++ b/drivers/media/video/pwc/pwc-v4l.c
@@ -309,7 +309,10 @@ static int pwc_vidioc_set_fmt(struct pwc_device *pdev, struct v4l2_format *f)
 	    pixelformat != V4L2_PIX_FMT_PWC2)
 		return -EINVAL;
 
-	PWC_DEBUG_IOCTL("Try to change format to: width=%d height=%d fps=%d "
+	if (pdev->iso_init)
+		return -EBUSY;
+
+	PWC_DEBUG_IOCTL("Trying to set format to: width=%d height=%d fps=%d "
 			"compression=%d snapshot=%d format=%c%c%c%c\n",
 			f->fmt.pix.width, f->fmt.pix.height, fps,
 			compression, snapshot,
@@ -318,14 +321,14 @@ static int pwc_vidioc_set_fmt(struct pwc_device *pdev, struct v4l2_format *f)
 			(pixelformat>>16)&255,
 			(pixelformat>>24)&255);
 
-	ret = pwc_try_video_mode(pdev,
+	ret = pwc_set_video_mode(pdev,
 				 f->fmt.pix.width,
 				 f->fmt.pix.height,
 				 fps,
 				 compression,
 				 snapshot);
 
-	PWC_DEBUG_IOCTL("pwc_try_video_mode(), return=%d\n", ret);
+	PWC_DEBUG_IOCTL("pwc_set_video_mode(), return=%d\n", ret);
 
 	if (ret)
 		return ret;
@@ -882,9 +885,7 @@ long pwc_video_do_ioctl(struct file *file, unsigned int cmd, void *arg)
 
 		case VIDIOC_STREAMON:
 		{
-			/* WARNING: pwc_try_video_mode() called pwc_isoc_init */
-			pwc_isoc_init(pdev);
-			return 0;
+			return pwc_isoc_init(pdev);
 		}
 
 		case VIDIOC_STREAMOFF:
diff --git a/drivers/media/video/pwc/pwc.h b/drivers/media/video/pwc/pwc.h
index 36a9c83b5f5dcc4d5762e87addd45807b6d212e0..16bbc6df9b075a82c4ec03b9f3553c2c22a80da5 100644
--- a/drivers/media/video/pwc/pwc.h
+++ b/drivers/media/video/pwc/pwc.h
@@ -275,7 +275,6 @@ extern int pwc_trace;
 extern int pwc_mbufs;
 
 /** functions in pwc-if.c */
-int pwc_try_video_mode(struct pwc_device *pdev, int width, int height, int new_fps, int new_compression, int new_snapshot);
 int pwc_handle_frame(struct pwc_device *pdev);
 void pwc_next_image(struct pwc_device *pdev);
 int pwc_isoc_init(struct pwc_device *pdev);