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

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On Thu, 17 May 2012, Chen Peter-B29397 wrote:

> > > It's reasonable to assume that other controllers in the future may have
> > > similar needs -- they may even require multiple PHYs to be notified
> > > about connect changes on multiple ports.  I see nothing wrong with
> > > implementing a callback just for this purpose.  Something like:
> > >
> > > 	void (*phy_connect_change)(unsigned port, int connected);
> > >
> > > Then in the port loop in ehci_irq(), you could do:
> > >
> > > 	if (unlikely(ehci->phy_connect_change && (pstatus & PORT_CSC)))
> > > 		(ehci->phy_connect_change)(i, pstatus & PORT_CONNECT);
> Hi Alan & Marek,
> 
> It is just FSL PHY's limitation, we can override ehci_irq at platform driver
> to finish the same thing. Better not to change common code, the cleaner the better
> for common code.

The common code is already full of special-case quirk code for devices 
from individual vendors.  One more won't hurt.

Besides, doing this in the interrupt handler is a hack, and it adds 
overhead to all the I/O operations.  Doing it as I suggested adds 
overhead only when a port changes state.

Also, IIRC Marek's proposal didn't check to see whether the controller 
was suspended (powered down) before trying to read the status register.

Alan Stern

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