FT4232H on ehci problem (was Re: usb/143832: [uftdi] Request support for FTDI FT4232H.)

[UEMURA Tetsuya]

> Now I have a problem with the device. When it is attached on ehci, it
> always stalls when I do a bit heavy communication over it. This doesn't
> happen with uhci (kldunload ehci or whatever).

I did further investigation myself and found that wMaxPacketSize is
0x0200 when the device was on ehci (0x0040 on uhci), and the device
seemed to work (at least not stall) on ehci if I changed
UFTDI_[IO]BUFSIZE to 512.

The device however stopped working on uhci with such a modification.

By the way, the official FTDI Linux driver found at
http://www.ftdichip.com/Drivers/VCP/Linux/ftdi_sio.tar.gz
also seemed to specify 512 as its buffer sizes.

Can anyone help me?

Regards.

-- 
UEMURA Tetsuya <t_uemura at macome.co.jp>
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