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List:       linux-usb-devel
Subject:    Re: [linux-usb-devel] changing values in endpoint?
From:       Alan Stern <stern () rowland ! harvard ! edu>
Date:       2005-04-29 13:44:21
Message-ID: Pine.LNX.4.44L0.0504290936360.5325-100000 () iolanthe ! rowland ! org
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On Thu, 28 Apr 2005, Adam Oldham wrote:

> So in essense, there is no way to change the poll
> interval for devices outside of getting the vendor to
> change the software on the device itself? 
> Resubmitting the URB like someone else suggested
> doesn't have any affect, that I can tell.

You need to be more careful in your choice of words because, whether you 
realize it or not, you've been asking two different questions:

     1.	How can the bInterval value stored in the endpoint 
	descriptor on the device be changed?

     2.	How can the polling interval be changed?

The answer to 1 is, as you surmised, to get the vendor to change the 
device's firmware.

The answer to 2 is completely different.  As David Brownell wrote, the
actual polling interval gets assigned at the time a driver submits an URB.  
You can tell the host controller driver to use any interval you want; you
don't have to use the value that's in the descriptor.  Just pass your
value to the usb_fill_int_urb routine.

Alan Stern



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