Re: usb_clear_halt in USB serial drivers

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On Wed, Jul 08, 2009 at 03:02:01PM -0400, Alan Stern wrote:
> On Wed, 8 Jul 2009, Greg KH wrote:
> 
> > On Tue, Jul 07, 2009 at 11:33:36AM -0400, Alan Stern wrote:
> > > Greg:
> > > 
> > > A lot of the USB serial drivers call usb_clear_halt in their open
> > > methods.  Are these calls really needed?
> > 
> > Hm, at least one was, in the whiteheat driver, I don't know about the
> > others, it might just have been copied around :(
> 
> I guess the usb_clear_halt calls in whiteheat_attach are really needed,
> as opposed to the calls in whiteheat_open.

Yes, I think so.  But I can't remember anymore, that was written over 9
years ago :)

> > > There are comments about this in several of the drivers, particularly
> > > whiteheat.  Most of them boil down to "work around HCD bugs".  As far
> > > as anyone knows there are no remaining bugs of this sort in the HCDs
> > > -- and if there were, it would be better to fix them instead of working
> > > around them.
> > 
> > Those HCD bugs were usually from a different operating system, so the
> > devices had wierd workarounds themselves to handle this.  Hopefully
> > those issues are also resolved in those operating systems now as well.
> > 
> > I have no problem taking them out where you think that they are not
> > needed, and seeing what happens.  Especially for things like the option
> > driver where it fixes real problems.
> 
> I'll take out the problem-causing calls from option and cypress_m8 and 
> leave the others, since they don't seem to be doing any harm.

Sounds good to me.

thanks,

greg k-h
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