Re: [PATCH 4/4] CI13xxx: Add USB host interrupt notifier

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On Tue, 15 May 2012, Marek Vasut wrote:

> > I'm not sure I really understand the purpose of all this.  Why does the
> > PHY driver need to know about every IRQ the host driver receives?
> 
> I use the .notify_event in ci13xxx to filter out this kind of event, read the 
> EHCI host register and then notify the PHY about the state of USB PCD.

Which state changes are you interested in?

Could the ehci-hcd driver include a hook to call the appropriate PHY
driver at the right times?

> > And why can't it call the PHY driver directly?
> 
> I don't want to pull any PHY code into the ci13xxx host driver, it's completely 
> separate hardware.

You don't have to pull code from anywhere.  Just add a hook for a
method call at the appropriate place.

Really, in the end this will depend on how the PHY drivers get
integrated with the rest of the USB stack.  There will be controllers
with no kernel-visible PHY, controllers with a single PHY, and maybe
controllers with a separate PHY for each port.  How can we describe
these settings in a way that lets the HCD provide the PHY driver with
the information it needs, using minimal overhead?

Somehow, I don't think that filtering every interrupt through one or
more PHY drivers is the best approach.

Alan Stern

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