Shawn,
On 12/05/2011 12:55 AM, Shawn Guo wrote:
> On Wed, Nov 30, 2011 at 05:45:36PM -0700, Stephen Warren wrote:
> [...]
>> static void tegra_gpio_irq_ack(struct irq_data *d)
>> {
>> - int gpio = d->irq - INT_GPIO_BASE;
>> + int gpio = d->hwirq;
>>
> Though it's working right now, I'm not sure it's safe enough. This
> only works when d->hwirq_base is 0, which is true for now. But I doubt
> it will be always true. I guess hwirq_base was introduced there for
> some reason. When some day irqdomain starts using this field, the
> above code starts being broken. IMO, the way that generic-chip.c is
> using to calculate the number, d->irq - gc->irq_base, is much more
> safer.
It does work as the GIC hwirq_base is non-zero. It was introduced
exactly so that no conversion of hwirq is needed for functions like
this. hwirq_base is the starting point local to the controller
numbering. Say you have gpio controller with 16 lines, but only the
upper 8 lines have interrupt capability. Then you would set hwirq_base
to 8 and nr_irq to 8. Then hwirq will always be set to 8-15.
Rob
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