[media] pwc: Allow dqbuf / read to complete while waiting for controls
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/pwc/pwc-v4l.c b/drivers/media/video/pwc/pwc-v4l.c
index 986dd5d..5376572 100644
--- a/drivers/media/video/pwc/pwc-v4l.c
+++ b/drivers/media/video/pwc/pwc-v4l.c
@@ -526,8 +526,24 @@
container_of(ctrl->handler, struct pwc_device, ctrl_handler);
int ret = 0;
- if (!pdev->udev)
- return -ENODEV;
+ /*
+ * Sometimes it can take quite long for the pwc to complete usb control
+ * transfers, so release the modlock to give streaming by another
+ * process / thread the chance to continue with a dqbuf.
+ */
+ mutex_unlock(&pdev->modlock);
+
+ /*
+ * Take the udev-lock to protect against the disconnect handler
+ * completing and setting dev->udev to NULL underneath us. Other code
+ * does not need to do this since it is protected by the modlock.
+ */
+ mutex_lock(&pdev->udevlock);
+
+ if (!pdev->udev) {
+ ret = -ENODEV;
+ goto leave;
+ }
switch (ctrl->id) {
case V4L2_CID_AUTO_WHITE_BALANCE:
@@ -590,6 +606,9 @@
if (ret)
PWC_ERROR("g_ctrl %s error %d\n", ctrl->name, ret);
+leave:
+ mutex_unlock(&pdev->udevlock);
+ mutex_lock(&pdev->modlock);
return ret;
}
@@ -751,8 +770,14 @@
container_of(ctrl->handler, struct pwc_device, ctrl_handler);
int ret = 0;
- if (!pdev->udev)
- return -ENODEV;
+ /* See the comments on locking in pwc_g_volatile_ctrl */
+ mutex_unlock(&pdev->modlock);
+ mutex_lock(&pdev->udevlock);
+
+ if (!pdev->udev) {
+ ret = -ENODEV;
+ goto leave;
+ }
switch (ctrl->id) {
case V4L2_CID_BRIGHTNESS:
@@ -841,6 +866,9 @@
if (ret)
PWC_ERROR("s_ctrl %s error %d\n", ctrl->name, ret);
+leave:
+ mutex_unlock(&pdev->udevlock);
+ mutex_lock(&pdev->modlock);
return ret;
}