Hi,
I am just writing a Linux driver for one of
our products (based on a 8051 controller with
integrated USB core).
I am using Linux 2.6.11.
The driver is not used only to talk to the
controller, but even the firmware for the controller
gets uploaded from the driver during start-up.
Normally the device get found on the USB bus with
PID_1. Then the driver uploads the firmware into the
device and the device reenumerates on the USB bus.
Afterwards the driver finds the device with PID_2.
This works without any problems.
An problem occurs, when I unload the kernel module
(after booting the device) and reload it afterwards
(without disconnecting the device).
In this case the driver will find the device with
PID_2, because it is already booted (this should not
be problem).
When the driver sends a bulk transfer (1 byte) to
the device and tries to read back the result of the
command as a second bulk transfer (1 byte), this
second transfer hangs in 99% of all cases (till
the timeout expires).
===================================================
/* allocate buffer */
buf = kmalloc (1001, GFP_KERNEL);
if (buf == NULL)
{
printk ("%s: Failed to allocate memory.\n",
TELOSI2C_MODULE_NAME);
return (-ENOMEM);
}
/* send reset command to reset endpoint */
buf[0] = 1;
ret = usb_bulk_msg (dev->udev,
usb_sndbulkpipe (dev->udev, dev->ep_reset_out),
buf, 1, &tmp, msecs_to_jiffies (3 * 1000));
if (ret < 0)
{
kfree (buf);
return (ret);
}
do
{
/* read result of reset command from reset endpoint */
ret = usb_bulk_msg (dev->udev,
usb_rcvbulkpipe (dev->udev, dev->ep_reset_in),
buf, 1, &tmp, msecs_to_jiffies (3 * 1000));
--- this call blocks ---
===================================================
What can cause this problem? The same device works under Windows
without these problems.
cu, Marco
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