From: John Mock <kd6pag@qsl.net>
To: linux-kernel@vger.kernel.org
Subject: USB driver troubles: OHCI vs. UHCI
Message-Id: <E1AyM9d-00022O-00@penngrove.fdns.net>
Date: Tue, 02 Mar 2004 18:30:37 -0800
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1428
Lines: 32

I've been using a homebrew USB driver for a PIC microprocessor development
board (Microchip PICkit, which uses the HID 'knothole'), based the 2.4.21
USB skeleton driver (with a few minor changes) for many months now on a 
PowerMac 8500 with an add-on OHCI board.  I tried compiling for a Sony 
VAIO R505EL, which uses the UHCI driver, with poor results.  

Under 2.4.22, it works the first time the device is opened, but hangs on
subsequent operations until the device is power cycled or the UHCI driver
is module is removed/re-installed again.

I tried updating it to 2.6.1-rc2 and it quickly gets an error, saying 

    [skel]_write - failed submitting write urb, error -22.

Thinking i had messed up the driver, i generated a current kernel (2.6.3)
on the PowerMac, and the updated driver worked the first time with the
OHCI board.

Is this a known problem with 2.6.xx, and if so, what does it mean??

Any idea what the skeleton driver isn't doing under 2.4.2x which causes
a device to enter a hung state on subsequent opens on UCHI (but not OHCI)?

As of a few minutes ago, i have a workaround.  But i'm still quite puzzled
and hope someone else has been here before.

				 -- JM
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