On Fri, 24 May 2013, Federico Manzan wrote:
> Increase the current arbitrary limit for isocronous packet size to a
> value large enough to account for USB 3.0 super bandwidth streams,
> bMaxBurst (0~15 allowed, 1~16 packets)
> bmAttributes (bit 1:0, mult 0~2, 1~3 packets)
> so the size max for one USB 3 isocronous transfer is
> 1024 byte * 16 * 3 = 49152 byte
>
> Signed-off-by: Federico Manzan <f.manzan@xxxxxxxxx>
So you decided to take matters into your own hands. Good for you!
> diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
> index caefc80..7ac137e 100644
> --- a/drivers/usb/core/devio.c
> +++ b/drivers/usb/core/devio.c
> @@ -1287,9 +1287,11 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
> goto error;
> }
> for (totlen = u = 0; u < uurb->number_of_packets; u++) {
> - /* arbitrary limit,
> - * sufficient for USB 2.0 high-bandwidth iso */
> - if (isopkt[u].length > 8192) {
> + /* arbitrary limit need for USB 3.0
> + * bMaxBurst (0~15 allowed, 1~16 packets)
> + * bmAttributes (bit 1:0, mult 0~2, 1~3 packets)
> + * sizemax: 1024 * 16 * 3 = 49152*/
> + if (isopkt[u].length > 65536) {
> ret = -EINVAL;
> goto error;
> }
A couple of suggestions for improvements:
First, new or updated multi-line comments should follow the accepted
formatting standard:
/*
* Start comment here...
* and end here.
*/
Second, it's confusing for the comment to mention that the limit is
49152 and the code to set the limit to 65536. They should agree on a
single value (probably 49152).
If you make those two changes, you can add
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Alan Stern
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