Markus Gothe nietzsche at lysator.liu.se
Wed Mar 2 10:07:21 UTC 2016

Im pretty sure their NCM devices are able to send supported NTB formats. At least the Huawei driver indicates this.

They just change  pointers to the structs for 16/32 bit mode.

//MDen 2 mar 2016 09:51 skrev Bjørn Mork <bjorn at mork.no>:
> Bjørn Mork <bjorn at mork.no> writes:
> > The Windows driver sends a "reset function" request after the "get NTB
> > parameters" request.  The Linux driver doesn't do that.  Might make a
> > difference.  And it sends another "reset function" request just when
> > you'd think the setup was complete, restarting it all.  Don't know why
> > it does that.  Makes no sense to me.  But we could try it just for
> > completeness.
> I had to reread the spec to see if there is any reasons there for us to
> do this, but I still cannot see any.  Assuming the device is conforming
> to spec that is, which it clearly isn't.  So we can add the reset to
> replicate Windows behaviour in case some buggy firmware expects it, but
> that is the only reason.
> Rereading the NCM spec regarding device behaviour on "set interface" was
> far more interesting. I can recommend Huawei to review the section
> "7.2 Using Alternate Settings to Reset an NCM Function".  In short, the
> device is supposed to reset all relevant settins to default when the
> host selects altsetting 0.  And one of those defaults is:
>   "reset the NTB format to NTB-16"
> So there you have it.  The device should never operate in NTB-32 unless
> the host/driver explicitly selected that mode.
> But whatever.  If Windows selects NTB-32, then we might have to do the
> same. It will complicate the driver - unnecessarily IMHO.  But I am
> hoping that we can avoid configuring any vendor or devices specific
> quirks for this, though.  Let's cross fingers that Huawei at least have
> implemented a working "get NTB format" (required for devices supporting
> NTB-32), so that we can automatically detect devices refusing to operate
> in NTB-16 mode.
> Bjørn
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