linux-kernel - Re: [PATCH 1/3 v2] GPIO: gpio-dwapb: Enable platform driver binding to MFD driver

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Date:	Tue, 9 Sep 2014 09:01:44 +0000
From:	"Shevchenko, Andriy" <andriy.shevchenko@...el.com>
To:	"Chen, Alvin" <alvin.chen@...el.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	"Kweh, Hock Leong" <hock.leong.kweh@...el.com>,
	"sebastian@...akpoint.cc" <sebastian@...akpoint.cc>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"Ong, Boon Leong" <boon.leong.ong@...el.com>,
	"gnurou@...il.com" <gnurou@...il.com>,
	"linus.walleij@...aro.org" <linus.walleij@...aro.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	"Westerberg, Mika" <mika.westerberg@...el.com>,
	"arnd@...db.de" <arnd@...db.de>,
	"dvhart@...ux.intel.com" <dvhart@...ux.intel.com>,
	"atull@...nsource.altera.com" <atull@...nsource.altera.com>
Subject: Re: [PATCH 1/3 v2] GPIO: gpio-dwapb: Enable platform driver binding
 to MFD driver

On Tue, 2014-09-09 at 01:50 +0000, Chen, Alvin wrote:
> > On Friday 05 September 2014 12:02:01 Shevchenko, Andriy wrote:
> > > > irq = irq_of_parse_and_map(node, 0); If (!irq) {
> > > > pp->irq = -1;
> > > > return;
> > > > } else {
> > > > pp->irq = irq;
> > > > }
> > > > Then the code looks strange.
> > > >
> > > > How do you think?
> > >
> > > If I understood correctly you messed up with hwirq vs. virq.
> > > Otherwise you have mention that you are using virq everywhere (I guess
> > > you may rename the field in the structure), but in this case the field
> > > in the platform_data looks a bit strange.
> > 
> > The field in platform_data should be the mapped virtual irq number, it makes no
> > sense to use the hwirq unless you also add a pointer to the domain in which
> > that hwirq exists.
> > 
> > Also the output of irq_of_parse_and_map() is a mapped irq, as the name
> > suggests.
> > 
> I agree with Arnd. Here, the 'irq' is 'virq'.
> Andriy, you may be confused by the code like 'irq_create_mapping'. For Quark case, it has 8 GPIO pins, and each pin can trigger
> interrupt, but all these interrupts are triggered by PCI irq which is shared. The 'irq' in pdata is PCI irq. As all GPIO interrupts connect to the PCI
> irq, once the GPIO interrupt is triggered, and the PCI irq handler will be called 'dwapb_irq_handler_mfd'. And in 'dwapb_do_irq', it will read the
> interrupt register to see the interrupt is triggered by which GPIO pin, and 'irq_create_mapping' is for this case.

Thanks for clarification. I take back my initial comment then.

-- 
Andy Shevchenko <andriy.shevchenko@...el.com>
Intel Finland Oy
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