Re: [RFC] Delay EHCI initialization until khubd is idle

[Greg KH <greg@xxxxxxxxx>]

On Tue, Sep 02, 2008 at 02:49:53PM -0400, Alan Stern wrote:
> On Tue, 2 Sep 2008, Greg KH wrote:
> 
> > On Tue, Sep 02, 2008 at 11:32:50AM -0400, Alan Stern wrote:
> > > Everybody:
> > > 
> > > Frans Pop has been bothered by the error messages that appear in the 
> > > system log when EHCI initialization interrupts the initialization of 
> > > devices attached to the companion controllers.
> > > 
> > > The patch below provides a way to prevent these messages from being
> > > generated, most of the time.  It forces EHCI initialization to wait
> > > until khubd is idle, which won't happen until all devices attached to a
> > > companion controller have been initialized and enumerated, though not
> > > necessarily probed.
> > > 
> > > Now this is cosmetic at best.  Devices will still suffer a short
> > > disconnection when EHCI starts up; the difference is that now the
> > > errors will affect the drivers bound to those devices rather than
> > > affecting khubd.  Since drivers tend to produce relatively few error
> > > messages when a disconnect occurs (unlike khubd which tends to complain
> > > a lot), the log remains cleaner.
> > > 
> > > In theory this might even be detrimental.  For example, it's possible
> > > that the delay might allow time for a USB flash drive to be mounted
> > > before it is disconnected, instead of being disconnected before
> > > usb-storage can bind to it.
> > 
> > Yeah, I would worry about this thing happening a lot, that's not good,
> > and can slow down the boot process even more.
> > 
> > If the messages are annoying people, can we just change them to
> > debugging levels instead?
> 
> I suppose so.  But what happens if someone plugs in a device and it 
> really does fail to initialize or enumerate?  Shouldn't that cause an 
> error message to appear?

Yes, that is true.

If people really are annoyed by the messages, they can easily turn them
all off :)

other than that, I don't have any suggestions, except that I don't think
we should apply this kind of change to the tree.

thanks,

greg k-h
--
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