Hello,
I am writing a driver for USB to Serial converter /bridge
having 4 serial ports .
I was going through the existing USB to Serial driver . I
have a few questions related to those . I would be glad to
receive responses to my queries .
1. "num_interrupt_in" field in the usb_serial_device_type
structure is for the device and not for the port .
I mean if there is a device which has INTERRUPT IN and BULK
OUT endpoints per port and has 4 such ports I would decalare
usb_serial_device_type with the fields poplulated as follows
.num_interrupt_in = 4,
.num_bulk_in = 0,
.num_bulk_out = 4,
.num_ports = 4,
2. what are the tx Credits for the edgeport adapter ? I
really didnt get a feel of what it means .
3. Do I need to maintain a buffer at the driver level . What
governs the desicion of having a buffer at the driver level.
In many sample drivers I found a separate buffer - e.g
pl2303.c , kobil_sct.c .
I guess it should be a good since we can only transmit 64
bytes ( maxPacketSize of endpoint ) in an URB and the
applications talking to serial device may send more bytes than these .
4. What should be the criteria used to select the size of
the buffer .
5. What is the significance of this step in "kobil_write()"
and "kobil_read_int_callback"
// someone sets the dev to 0 if the close method has been called
port->interrupt_in_urb->dev = port->serial->dev;
Thanks ,
Monali.
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