Re: [PATCH] Fix OTG HNP for hub.c (USB OTG HNP (can you find any other appropriate TLAs?)

<snip>

> > The behavioral difference would be that WHEN ("not 'IF'")
> > the whitelist (which is very easily checked against product
> > documentation) diverges from the list of configured drivers
> > (no easy way to crosscheck that and docs) things would not
> > act the same.
>
> I guess HNP should be offered for peripherals even if not
> on whitelist, but only peripherals on whitelist (with HNP
> or not) should be allowed.

Or maybe we run a set_feature (b_hnp_enabled) just before the
suspend... can we do that dave?? It doesn't seem really correct when
typing... but...

If I'm not wrong... every device can accept a b_hnp_enable set_feature
command... if the controller doesn't support it just return a
"stall".. or something like that... so... we could just forget about
the whitelist for now.. can't we?

If the device supports HNP it will get the b_hnp_enable command and
after a_host enters in suspend mode... it will try to do HNP (if the
user wants...)

>
> > This is more or less what you were trying to achieve,
> > yes?  But it leads to surprising behavior in cases
> > like:
> >
> >    * hook up non-OTG peripheral #1 ... acts just
> >      the way you'd normally expect
> >
> >    * hook up OTG peripheral #2 ... surprise!  it
> >      refuses to act as a peripheral at first.
> >
> > The "principle of least astonishment" argues that
> > the "peripheral #1" model should be followed for
> > as long as possible.  Customer service calls would
> > be a lot simpler too...
>
> Yeh I guess in that case it needs to wait for autosuspend
> until #1 is done.
>
> But if #2 is not on whitelist and can do HNP, then
> it just gets rejected and never gets it's HNP opportunity.
>
> Hmmm...
>
> Tony
>


-- 
Best Regards,

Felipe Balbi
[email protected]

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