Re: [RFC PATCH 3/5] pxa: clean up the legacy SSP API

[Russell King - ARM Linux <linux@arm.linux.org.uk>]

On Thu, Apr 30, 2009 at 10:31:53AM +0800, Eric Miao wrote:
> On Thu, Apr 30, 2009 at 2:51 AM, Russell King - ARM Linux
> <linux@arm.linux.org.uk> wrote:
> > The transfers happen under control of PCON not the PXA; PCON asserts a
> > GPIO to activate the DMA to control when the transfer happens.
> 
> That's too bad then. Does that GPIO act like a chip select or it's just a
> signal to inform the host to do a transfer? And it also depends on the
> SCLK direction.
> 
> If the GPIO behaves like an IRQ to inform the host for a transfer, maybe
> the driver can arrange a transfer initiated by that event.

I don't know what the timing requirement is.  What I do know is what
the current code does, which is to use the signal to control the
transmit DMA when PCON wants to transfer data.

Now, remember that PCON has a habbit of resetting the PXA when things
happen that it doesn't like, I really don't want to go round
experimenting with this thing; as already stated it's really not worth
trying to merge this code if that's what will be required.