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I occasionally need to connect to a serial device and in the past have
used minicom and the Keyspan USA-19HS adapter. It has worked
flawlessly. Once I upgraded, I could never seem to make this work. The
kernel recognizes the adapter, it gets properly assigned as
/dev/ttyUSB0, and minicom seems to transmit data to it (as evidenced by
the green LED on the device that flashes whenever I hit a keystroke.
The problem is, it never returns any data. If I use VMWare to boot up
WinXP I can access anything connected to the adapter, but it grinds me
to have to boot up 'doze for that purpose.
This morning I ran into the problem again and did some googling to see
anyone else had this problem. I found this entry in
http://www.kernel.org/pub/linux/kernel/v2.6/snapshots/old/patch-2.6.20-git4.log
Date: Wed Jan 3 15:36:25 2007 +0100
fix for bugzilla #7544 (keyspan USB-to-serial converter)
At least the Keyspan USA-19HS USB-to-serial converter supports
two different configurations, one where the input endpoints
have interrupt transfer type and one where they are bulk endpoints.
The default UHCI configuration uses the interrupt input endpoints.
The keyspan driver, OTOH, assumes that the device has only bulk
endpoints (all URBs are initialized by calling usb_fill_bulk_urb
in keyspan.c/ keyspan_setup_urb). This causes the interval field
of the input URBs to have a value of zero instead of one, which
'accidentally' worked with Linux at least up to 2.6.17.11 but
stopped to with 2.6.18, which changed the UHCI support code handling
URBs for interrupt endpoints. The patch below modifies to driver to
initialize its input URBs either as interrupt or as bulk URBs,
depending on the transfertype contained in the associated endpoint
descriptor (only tested with the default configuration) enabling
the driver to again receive data from the serial converter.
Greg K-H reworked the patch.
Signed-off-by: Rainer Weikusat <rweikusat@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
As you'll note, the keyspan stopped working at 2.6.18, which is the
kernel used by CentOS 5. My question is whether or not this bug still
exists in CentOS5 or if someone is successfully using the Keyspan with
CentOS5.
Thanks!
Barry
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