What transfer flags should usbfs2 expect userspace to set?

I have opinions on most of the transfer flas, but I'm unsure about
URB_NO_FSBR.  usbfs allows it to be set, although it looks like a hack
since the other flags are redefined as USBDEVFS_* and that one isn't.
LDD3 says this flag is only used by the uhci host controller driver.
Why was this exposed in usbfs?


Also, could some USB gurus check my initial opinions on the other
transfer flags:

Userspace shouldn't be allowed to set URB_NO_TRANSFER_DMA_MAP and
URB_NO_SETUP_DMA_MAP, since usbfs2 should set the policy on whether
usbfs2 or the USB core does DMA mapping.

URB_NO_INTERRUPT also should be disallowed, since my code relies on
the URB completion function being called for every URB.

URB_SHORT_NOT_OK is redundant, since userspace can detect a short read
from the return value of the system call.  Or is there a deeper reason
for setting this flag?

URB_ISOC_ASAP should be used automatically, unless the user specifies
the start frame through an ioctl.

URB_ZERO_PACKET should be allowed for buggy hardware.  However, it seems
like this should be a per-endpoint (or per-device) flag, rather than a
per-URB flag.  It would be nice if there was a file in sysfs so that
there could be a udev rule to set this flag.

Sarah Bailey

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