Re: functionfs on dwc3, xhci host: endpoint cannot be used in both directions ?

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Hello,

On Tue, Jan 24, 2017 at 12:20 AM, Felipe Balbi
<felipe.balbi@xxxxxxxxxxxxxxx> wrote:
> Seems like HW engineer wanted these last few endpoints to *not* support
> full USB3 packets. They are probably supposed to be used for Isochronous
> and/or Interrupts endpoints. At some point we need to support this as
> well. During initialization we should read FIFO size configuration and
> extract wMaxPacketSize for $endpoint from the HW.

If my understanding of your register explanation is correct, the >9 IN
endpoints could still work as bulk in LS/FS speeds (I don't have the
board at hand to try right now). If this is correct, won't your patch
(in your testing/next branch) make these endpoints unusable for bulk
use even in LS/FS ?

A bit more generally, I have the feeling (from reading epautoconf.c
and f_fs.c) that the endpoint dispatching (and hence, endpoint
capabilities) lacks the notion of speed (SS has it, kind of, via the
companion descriptor argument in epautoconf.c). I noticed something a
few weeks back which may come from this lack: when I tried only
populating the HS descriptors, the host xHCI would complain about
non-standard endpoint size (64B instead of HS-required 512B). In my
understanding, this is because f_fs.c allocates endpoints using the
first populated descriptor set (in LS/FS, then HS, then SS order), and
epautoconf.c overwriting the buffer size to 64 on non-SS bulk
descriptors.

I think extending such API is over my head still. Do you have ideas on this ?

FWIW, the Intel Edison (the board I'm using as device) is not USB 3
capable despite dwc3 usage. If my undrstanding is correct, it is
because it lacks the USB 3 companion phy, and of course does not
expose the corresponding tracks on the expansion connector (would it
be possible to host the companion outside the edison module ? I have
no idea how it is supposed to interract with the dwc3 and USB 2 phy).

Regards,
-- 
Vincent Pelletier
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