On Wed, Mar 23, 2011 at 05:28:29AM -0400, Alan Cox wrote: > On Tue, 22 Mar 2011 20:43:47 -0700 > Guenter Roeck <guenter.roeck@xxxxxxxxxxxx> wrote: > > > This patch adds support for the I2C interface of the Devantech USB-ISS > > Multifunction adapter. > > > > Signed-off-by: Guenter Roeck <guenter.roeck@xxxxxxxxxxxx> > > --- > > The driver has one problem: It competes with the cdc_acm driver for device > > access. Copying the usb mailing list in the hope that someone can tell me > > if there is a way to prevent this from happening. > > From the look of the code you actually want to be sitting on top of > cdc_acm. > Ok, I'll see if I can do that. > > > +/* Send command to device, and get response. */ > > +static int devantech_usb_transfer(struct i2c_devantech_iss *dev, int len) > > +{ > > + int ret, actual; > > + > > + if (len <= 0 || len > ISS_MAX_TRANSFER_LEN) > > + return -EINVAL; > > + > > + ret = usb_bulk_msg(dev->usb_dev, > > + usb_sndbulkpipe(dev->usb_dev, dev->ep_out), > > + dev->buffer, len, &actual, > > + ISS_USB_TIMEOUT); > > + > > + if (!ret) { > > + ret = usb_bulk_msg(dev->usb_dev, > > + usb_rcvbulkpipe(dev->usb_dev, dev->ep_in), > > + dev->buffer, sizeof(dev->buffer), > > + &actual, ISS_USB_TIMEOUT); > > + if (!ret && actual > 0) > > + ret = actual; > > + } > > + return ret; > > +} > > The whole driver seems to boil down to sending and receiving message > blocks to the bulk endpoint - yes ? > Yes > > + dev->usb_dev = usb_get_dev(interface_to_usbdev(interface)); > > + dev->interface = interface; > > + > > + /* setup i2c adapter description */ > > + dev->adapter.owner = THIS_MODULE; > > + dev->adapter.class = I2C_CLASS_HWMON; > > Doesn't seem to be HWMON ? > You lost me there. Why not ? Many if not all I2C bus drivers register as I2C_CLASS_HWMON. > > The rest looks like the device doesn't pretend to be CDC ACM class, but > is CDC-ACM class with the "device" the other end talking to the other end > of the serial port. > > In fact it would be an interesting test to open the serial port and write > your commands to it from user space to see what happens. If I read the > code right it'll work fine. > Yes, it should work. That is what is done in Windows. > From a tty perspective it would probably make sense to adjust the driver > to be a line discipline sat on CDC-ACM. > > I am *very* wary of removing it from the CDC_ACM side because people may > be using the CDC-ACM userspace directly for existing projects and would > get a nasty surprise and breakage. > Same here. Not likely for existing projects (the device is brand new), but at some point someone might want to use it. > If setting the tty to raw 8bit noecho and firing commands over the > virtual interface works then turning your driver into an ldisc is pretty > trivial. The ldisc interfaces provide data received and allow data writes > through the relevant tty. > I'll try. Thanks, Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html