Discussion:
Problem with large writes to FTDI USB serial converter and alternate UHCI driver
Yegor Yefremov
2008-01-11 14:02:05 UTC
Permalink
Hi All,

I have the same problems as Ian Abbott had late 2003
http://www.mail-archive.com/linux-usb-***@lists.sourceforge.net/msg11919.html.
I know I should use 2.6 kernel, but at the moment I have to add new
functionality one of our platform that was introduced with 2.4 kernel
and there are also a lot of our own changes that will take a lot of time
to port them.

My system is ARM9 with 2.4.32 (I found only few changed between our
kernel and 2.4.36) kernel. FTDI chip will be attached to the VIA VT6212
HC. At first I tried to use usb-uhci.c driver, that solved problems with
data transfer, but introduced some new problems such as if device was
attached after system boot it wasn't correctly detected (if I execute
the detection with the debugger step by step there is no problem -
timing or synchronization issue???):

debian:~# hub.c: new USB device 00:06.0-1, assigned address 6
usb.c: not enough configurations
usb.c: unable to get device 6 configuration (error=-22)
hub.c: new USB device 00:06.0-1, assigned address 7
host/usb-uhci.c: uhci_submit_urb: pipesize for pipe 80000780 is zero
host/usb-uhci.c: uhci_submit_urb: pipesize for pipe 80000780 is zero
host/usb-uhci.c: uhci_submit_urb: pipesize for pipe 80000780 is zero
host/usb-uhci.c: uhci_submit_urb: pipesize for pipe 80000780 is zero
host/usb-uhci.c: uhci_submit_urb: pipesize for pipe 80000780 is zero
usb.c: unable to get device descriptor (error=-90)

Then I tried to reduce the size of the urb pool in ftdi_sio.c as
reported by Ian. With the number of NUM_URBS == 1 I can transfer data
with small baudrates (115200bit/s), but there is no chance for high
baudrates as 3MBit/s. The latter can be achieved with the NUM_URBS > 3
but < 32 (initial value).

Is there any patch to fix uhci.c + ftdi_sio.c or usb-uhci.c problem?

Thank you in advance.

Best regards.
Yegor



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