On Tue, Dec 6, 2011 at 8:43 AM, Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> wrote: > The driver who binds everything is the bridge driver. In your case, it is > the au0828 driver. > > What you're experiencing seems to be some race issue inside it, and not at > xc5000. > > On a quick look on it, I'm noticing that there's no lock at > au0828_usb_probe(). > > Also, it uses a separate lock for analog and for digital: > > mutex_init(&dev->mutex); > mutex_init(&dev->dvb.lock); > > Probably, the right thing to do would be to use just one lock for both > rising > it at usb_probe, lowering it just before return 0. This will avoid any open > operations while the device is not fully initialized. Btw, newer udev's open > the analog part of the driver just after V4L register, in order to get the > device capabilities. This is known to cause race conditions, if the locking > schema is not working properly. Just to be clear, we're now talking about a completely different race condition that has nothing to do with the subject at hand, and this discussion should probably be moved to a new thread. That said, yes, there is definitely a race (if not two) in there to be tracked down. I know of a couple of users who upgraded to more recent kernels and started experiencing breakage on module load where there was none before. This could obviously be dumb luck in that perhaps the timing changed slightly, or it could be some change in the core code which created a new race. I haven't had the time/energy to dig into the issue (compounded by the fact that these sorts of issues are notoriously difficult to debug when it cannot be reproduced locally by the developer). The notion that this is something that has been there for over a year is something I only learned of in the last couple of days. All the complaints I had seen thus far were from existing users who were perfectly happy until they upgraded their kernel a couple of months ago and then started seeing the problem. Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
