Hi all:
I have some questions about bandwidth calculation
1. why tt time need to include one maxp bus time ?
qh->tt_usecs = NS_TO_US (think_time +
usb_calc_bus_time (urb->dev->speed,
is_input, 0, max_packet (maxp)));
2. in tt_available, below is used to check whether tt time is bigger than 125us
if (125 < usecs) {
int ufs = (usecs / 125);
int i;
for (i = uframe; i < (uframe + ufs) && i < 8; i++)
if (0 < tt_usecs[i]) {
ehci_vdbg(ehci,
"multi-uframe xfer can't fit "
"in frame %d uframe %d\n",
frame, i);
return 0;
}
}
is it possible tt time bigger than 1 uframe?
3. below is the fomula to calculate bus time
Full-speed (Input)
Non-Isochronous Transfer (Handshake Included)
= 9107 + (83.54 * Floor(3.167 + BitStuffTime(Data_bc))) + Host_Delay
what is 9107 and 3.167 used for?
(9102 is not equal to FS bit time * FS protocol overhead)
Thanks for your help in advance,
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