Re: USB driver troubles: OHCI vs. UHCI

[Greg KH <greg@kroah.com>]

On Tue, Mar 02, 2004 at 06:30:37PM -0800, John Mock wrote:
> 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.

Sounds like a problem with your driver.

> 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??

No it isn't.

> 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.

Care to post the driver?

thanks,

greg k-h