On Fri, 20 Jan 2006 [EMAIL PROTECTED] wrote:
> Hi,
>
> I'm currently coding a device driver for a high speed device.
> Unfortunately,
> the test have shown, that the transfer rate is real slow.
>
> The code is as follows:
>
> urb = usb_alloc_urb( 0, GFP_KERNEL );
> .....
> usb_fill_bulk_urb( urb, usb_dev, pipe, data, len,
> wcam_usb_api_blocking_completion, context );
> init_completion( &sbuf->done );
> .....
> urb->actual_length = 0;
> status = usb_submit_urb(urb, GFP_ATOMIC);
> .....
> if ( status == 0 )
> {
>
> wait_for_completion( &sbuf->done );
>
> }
>
> The memory to transfer is 307200 Bytes, the enpoint transfers up to 320
> Byte.
> BTW, is it possible to increase the Bulk transfersize beyond the 512 Bytes
> ?
Your question isn't clear. No, it's not possible for bulk endpoints to
transfer more than 512 bytes per packet. Yes, it is possible for
urb->transfer_length to be larger than 512 (the host controller driver
will divide the data up into packets).
> Now, what I get is, that the completion handler is called 960 times in 120
> ms, which means
> that the driver uses a single microframe to transfer 320 Bytes.
I don't understand. The code above calls usb_submit_urb only once, so the
completion handler should be called only once. Not 960 times.
> So my question is: How do I have to configure the bulk transfer to get the
> maximum speed ?
In your code above, store all 307200 bytes in data and set len to 307200.
Alan Stern
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