Re: loading firmware while usermodehelper disabled.

On Sat, 31 Dec 2011, Matthew Garrett wrote:

On Fri, Dec 30, 2011 at 04:22:06PM -0800, Linus Torvalds wrote:

quoted

It's isight_firmware_load(), in the isight_firmware driver. The driver
doesn't actually do anything but load the firmware, and is apparently
not very good at that either.

It should either fake a disconnect and reconnect of the device (and
let the reconnect then load the firmware through udev or something) or
it should just save the firmware image in memory from the original
load, and make the resume just re-initialize it - not load it.

Mm. My recollection is that these devices retained their firmware over 
suspend/resume, so wouldn't resume with a USB id that matched the driver 
and so this code shouldn't be called. It seems that either I was 
horribly wrong about that, or something's changed in the USB layer 
that's resulting in them resetting themselves. Newer devices don't 
require this, so I'll need to try to chase up some older hardware to 
figure out what's going on.

Nothing has changed in the USB layer -- it has always been true that
devices could be reset during a suspend/resume cycle.  This isn't a
matter of how the stack is written or anything like that; some
motherboards simply do not provide suspend power to their USB
controllers.  Or the firmware reinitializes the controllers and
attached devices during resume, forcing Linux's USB core to reset
every device on the affected buses.

When it comes to suspend/resume, there are almost no guarantees.  :-(

Alan Stern