On Fri, 9 Aug 2013, Christian Lamparter wrote:

quoted

After loading firmware, a reset generally is necessary.  Some devices 
will do it themselves; others require you to call usb_reset_device().

This makes things complicated. Because, as far as I remember,
usb_reset_device() will cause the current driver to be unbound
unless its called during .probe, right?

If the driver defines pre_reset and post_reset methods, it won't get 
unbound during a reset.

You see, ath9k_htc loads its firmware asynchronously in ".probe"
(ath9k_htc's .probe routine finishes before the firmware is
retrieved via the firmware loader helper... so part of the
firmware download is done in a firmware_complete callback
on a workqueue). 

So, if we call usb_reset_device there and the driver is unbound
and later rebound. the next ath9k_htc .probe will start again and
again and again not knowing that it is already initialized 
(and we have a loop).


This could be solved, if the devices changes the usb-id again 
when a proper "wifi" ath9k_htc firmware was downloaded. So, the
driver would know that it doesn't have to download and reset
the device... But we need a "free" USB-ID for that.

What about a "get firmware version" sort of thing?  There really should 
be a way for the driver to tell whether the firmware has already been 
updated.

Alan Stern