On Monday, 28 May 2007 13:15, Pavel Machek wrote: > Hi! > > > > > > What exactly is the problem we see here? The timeout of the firmware loader? > > > > > What goes wrong with frozen userspace, usually there is only a netlink > > > > > message sent from the kernel, which should be received and handled > > > > > just fine when userspace is running again. > > > > > > > > Driver calls request_firmware in the resume method. The userspace helper > > > > can't be run because it's been frozen, so the firmware never gets loaded > > > > and the call times out. The driver then fails to resume. While all this > > > > is happening, the rest of the kernel is blocking on that resume method. > > > > The firmware can be loaded once userspace has been started again, but by > > > > that time the driver has given up. > > > > > > Seems, that's just the broken synchronous firmware loading interface > > > with the useless timeout handling. The nowait version of the same loader > > > doesn't time out, and should not have that problem. The sync version > > > should be removed from the kernel, it just causes all sorts of problems > > > since it exists. > > > > > > Userspace should handle the async request just fine when it comes back > > > running, regardless of the time it was submitted. > > > > Okay, so the solution is to convert the drivers to use > > request_firmware_nowait() instead of request_firmware() in their .resume() > > routines. > > You'll just get deadlock at different level (and more rare). > > Imagine disk with its firmware on NFS and NFS with its firmware on > disk. Yeah, I've just given the very same example in another message. :-) I believe the only _solution_ would be to load the firmware into memory before the suspend and use the in-RAM copy to upload it into the device in .resume(). A PM_PRE_FREEZE notifier could be used for that just fine, BTW. Greetings, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
