Messages in this thread | | | Date | Mon, 2 Jan 2012 21:50:28 +0000 | From | Matthew Garrett <> | Subject | Re: loading firmware while usermodehelper disabled. |
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On Mon, Jan 02, 2012 at 01:27:03PM -0800, Linus Torvalds wrote:
> If we didn't load the firmware before the suspend, then the resume > function of a device sure as hell had better not load it at resume > time either.
If the hardware has lost its state then refusing to load the firmware at resume time isn't going to leave you with a working device.
> And for chrissake, don't bother making it more complicated than it is, > just for some theoretical hardware or situation that nobody cares > about.
It's not theoretical hardware. This appears to be the current behaviour of the isight devices. If you reboot they retain their firmware. If you suspend, they don't. So if we have a flow like this:
1) user boots from cold. Device comes up with generic USB ID. 2) isight_firmware loads and binds. Firmware is loaded. Device disconnects and reconnects with an ID that's bound by the UVC driver. 3) user reboots. Device comes up with UVC ID. isight_firmware doesn't bind. 4) user suspends. 5) user resumes. isight_firmware binds and attempts to load firmware.
then just caching the firmware is inadequate - we had never previously seen the device on this boot, so we've never loaded it in order to cache it. isight_firmware could unconditionally load the firmware on module load just in case a device is plugged in, but that seems even less elegant than caching it.
Now this is obviously somewhat mitigated because isight_firmware won't have been autoloaded at (3), so won't be there at (5) unless the user's manually loaded it. But insmodding a driver shouldn't result in stuff breaking later.
-- Matthew Garrett | mjg59@srcf.ucam.org
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