Re: patch usb-iowarrior.patch added to gregkh-2.6 tree

On Tue, 20 Feb 2007 11:57:14 -0500 (EST), Alan Stern <[email protected]> wrote:
> On Tue, 20 Feb 2007, Guido Körber wrote:

> > There is no situation where a USB device sends multiple reports in  
> > the same packet.
> 
> I've never seen it happen myself, but Pete Zaitcev says he has:
> 
> http://marc.theaimsgroup.com/?l=linux-usb-devel&m=116545264427365&w=2

That it true, I have seen it. However, it is not an argument for the use
of maxPacketSize to size URB-level transfers. In fact, I am yet to see
a good argument for it. In case of Microsoft Keyboard bubbling, for example,
there's no telling what the size should be... Maybe 6 bytes, maybe 20,
maybe 200. But whatever it is, it's not a maxPacketSize.

The same is true for our usb-serial code, where the infestation of
maxPacketSize is most severe. Perhaps I should submit a patch for Greg
which rips it out and places something like

 if (speed == USB_SPEED_HIGH)
   size = 192
 else
   size = 16

The iowarrior fix is keyed on vendor/device like this:

	if((dev->interface->cur_altsetting->desc.bInterfaceNumber == 0) && 
(dev->product_id == USB_DEVICE_ID_CODEMERCS_IOW56))

We do not want to sprinkle our code with such tests if we can help it.
Sounds like a good opportunity for a real fix (with sensible line size
and whitespacing, too).

-- Pete

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