[linux-usb-devel] Re: [PATCH] Eagle and ADI 930 usb adsl modem driver

[Duncan Sands]

On Wednesday 2 November 2005 09:45, Oliver Neukum wrote:
> Am Mittwoch, 2. November 2005 09:03 schrieb Greg KH:
> > On Wed, Nov 02, 2005 at 08:54:22AM +0100, Duncan Sands wrote:
> > > > > + * sometime hotplug don't have time to give the firmware the
> > > > > + * first time, retry it.
> > > > > + */
> > > > > +static int sleepy_request_firmware(const struct firmware **fw, 
> > > > > +		const char *name, struct device *dev)
> > > > > +{
> > > > > +	if (request_firmware(fw, name, dev) == 0)
> > > > > +		return 0;
> > > > > +	msleep(1000);
> > > > > +	return request_firmware(fw, name, dev);
> > > > > +}
> > > > 
> > > > No, use the async firmware download mode instead of this.  That will
> > > > solve all of your problems.
> > > 
> > > Hi Greg, it looks like you understand what the problem is here.  Could
> > > you please explain to us lesser mortals ;)
> > 
> > If you use the async mode, there is no timeout.  When userspace gets
> > around to giving you the firmware, then you continue on with the rest of
> > your device initialization (don't block the usb probe function though.)
> 
> How would you handle errors in setting up the device?
> A driver cannot reject a device after probe, yet you need to handle
> errors appearing only after the firmware is in the device.

Isn't that the case anyway with the sync version?  After all, sync loading
of firmware from the probe method is unacceptable, since it can block khubd
for a long time (also, if the firmware lives on a USB device that gets
disconnected just as probe for the device that loads firmware is called,
or some variation of this theme, couldn't horrible blockage happen?).

Ciao,

D.