Mauro,
This patch simplifies the locking by moving the em28xx_init_extension() call
until em28xx_usb_probe() has finished with the dev->lock mutex. It therefore
makes the second and subsequent "plugging" events logically identical to the
first "plugging" event when the em28xx-dvb and em28xx-alsa modules must be
loaded (i.e. registered).
Basically, em28xx_usb_probe() requests that em28xx-dvb be loaded and also
triggers udev to initialise the V4L2 devices. These two events are serialised by
the dev->lock mutex but the order that they happen in is undefined. But this has
always been the case anyway.
Signed-off-by: Chris Rankin <rankincj@xxxxxxxxx>
Cheers,
Chris
--- linux/drivers/media/video/em28xx/em28xx-cards.c.orig 2011-09-25 22:51:59.000000000 +0100
+++ linux/drivers/media/video/em28xx/em28xx-cards.c 2011-09-25 23:24:06.000000000 +0100
@@ -3005,10 +3005,6 @@
goto fail;
}
- mutex_unlock(&dev->lock);
- em28xx_init_extension(dev);
- mutex_lock(&dev->lock);
-
/* Save some power by putting tuner to sleep */
v4l2_device_call_all(&dev->v4l2_dev, 0, core, s_power, 0);
@@ -3243,6 +3239,13 @@
*/
mutex_unlock(&dev->lock);
+ /*
+ * These extensions can be modules. If the modules are already
+ * loaded then we can initialise the device now, otherwise we
+ * will initialise it when the modules load instead.
+ */
+ em28xx_init_extension(dev);
+
return 0;
err:
