areversat wrote:
Sorry i'm late responding to this mail but i had a chat with benoit
about this patch and we were wondering why it wasn't good since the
exact same code is used to initialize interval for INTERRUPT URBs could
you explain us why ? Thanks
Read the USB spec about how the bInterval field is defined,
and compare that to how the urb->interval filed is defined.
If the interrupt transfers have broken locking, or they don't fill
in highspeed interval correctly (same formula as below, your code
would be correct for low and full speeds) ... I'm not surprised.
Looks like the kernel is going to have to do this, since I don't
see a way that userspace can pass this interval down. However:
- That epnum_to_ep_desc() result shouldn't be used without a bit
more locking; else the config could change from under usbfs.
- The correct formula is "interval = (1 << (ep_desc->bInterval - 1))"
for all device speeds. (For high speed devices the units will
be microframes.)
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