On Wednesday 15 Jan 2003 10:12 pm, Dan Streetman wrote:
> On Wed, 15 Jan 2003, David Brownell wrote:
> >> Hmm, so should the conversion from bInterval to ms-interval happen in
> >> the driver, or in the core? It seems to me that it would be better to
> >> handle that conversion in the core...?
> >
> >We had that discussion last summer, and the resolution
> >was that fill_int_urb() does it ... ISO drivers don't
> >have such a utility to call.
>
> mmm, that's too bad, it seems unfortunate to duplicate that conversion in
> all iso drivers (and int drivers that don't use fill_int_urb)...
>
> Wouldn't it make sense to have a conversion function in usb.c,
> something like:
>
> inline int bInterval_to_ms(unsigned char bInterval, int speed, int isoc)
> {
> if (USB_SPEED_HIGH == speed)
> return (2^(bInterval-1)) * 125;
> else if (isoc)
> return (2^(bInterval-1));
> else
> return bInterval;
> }
inline int epint_to_urbint(unsigned char bInterval, int speed, int isoc)
{
if(isoc)/*section 5.6.4 Iso transfers*/
{
/*Table 9-13 Stadard Endpoint desc.*/
if(speed == USB_SPEED_HIGH ||speed == USB_SPEED_FULL ){
return 1<< (bInterval-1);
}
/*shouldn't get here, since low speed ISO's arn't supported by USB*/
}else /*Section 5.8 interrupt transfers*/
{
/*Table 9-13 Stadard Endpoint desc.*/
if(speed == USB_SPEED_HIGH ){
return 1<< (bInterval-1);
}
/* Full or low speed */
return bInterval;
}
}
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