On 02/01/12 23:00, Matthew Garrett wrote: > On Mon, Jan 02, 2012 at 02:46:56PM -0800, Linus Torvalds wrote: > >> It's *trivial* to attach the firmware driver and load the firmware >> even if the firmware isn't needed - because you know it *will* be >> needed if somebody suspends. Why not just do that? Why make up these >> horrible problems that are totally irrelevant? > > It means adding complexity to drivers that don't currently care about > it, and carrying that cost even for hardware that doesn't need it. It > can certainly be made to work, but it's inelegant. We could avoid this > specific instance of the problem by just punting responsibility to > userland instead. > > It's clear that we can solve this. All I'm saying is that just making > the firmware loader cache things isn't a solution in itself. In this > specific case, it means merging the isight_firmware driver into > uvcvideo, which is something the uvcvideo maintainer didn't seem keen on > a few years ago. > Rather than merging the drivers we could make the uvcvideo (or any other generic driver) driver expose a "subdriver" interface that allows another module to bind to the specific ID and add extra handling to certain events. We could then use that interface to provide a firmware driver for each device that needs it. The firmware driver could bind to the bootstrap device and to the uvcvideo subdriver interface and it would then have all the lifetime info we need. [Credit to Linus for suggesting this idea] You mensioned earlier about not being able to tell the difference between a device that needs firmware and one that needs flash (e.g. they use exactly the same ids). It doesn't really matter - we just assume that it might need firmware and load it anyway. It uses more memory but is robust. Also, as Linus mensioned, for some devices we just don't care. For example, if we drop a video call over suspend it's not ideal but it doesn't prevent the system from resuming. Lets concentrate on fixing all the cases that could prevent resume (the "99%") and fix the other devices later. Thanks, Jack -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
