Alan Stern wrote:

Will that work in a composite gadget?  What if some functions only support
one speed, so that different sets of endpoints get allocated for the
different speed configs?

Composite gadget -- sure. Remember the focus of that routine is on "bulk-only" drivers, which have no reason not to offer identical functionality at both device speeds. Maxpacket is the ONLY difference in such cases (other than bInterval), and bulk is always 512 at high speed.

For that matter, I think even ISO drivers should offer the
same functionality ... they can use the same maxpacket and
period at both speeds.  In addition to altsettings giving
higher bandwidth options, of course!


Wouldn't it be easier for a dual-speed function driver simply to have two
endpoint descriptors, passing one of them to usb_ep_autoconfig() when
intializing the full-speed configuration and passing the other when
intitializing the high-speed config?  I would be happy if the function

I think it's much simpler to have dual-speed drivers just copy a few bEndpointAddress values, and bMaxPacketSize0 (three lines, one place).

One of the reasons "bulk-only" is interesting is because
drivers CAN take a really simple approach to setting up
the configurations.

I thought about passing two endpoints to usb_ep_autoconfig(),
but couldn't come up with anything that a single-endpoint
call wouldn't do just as well, and more simply.  Even for
high bandwidth ISO/INTR.


driver merely had to initialize the descriptors' maxpacket values to 64
and 512 respectively, relying on autoconfig to adjust them appropriately.

Well, if you've initialized high speed bulk to 512, you could just pretend autoconfig did exactly that ... and that you called it a few more times, with a few different parameters. :)

- Dave




Alan Stern







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