Question about SPIs' interrupt trigger type restrictions

[richard clark]

Hi Marc,

For below code snippet about SPI interrupt trigger type:

static int gic_set_type(struct irq_data *d, unsigned int type)
{
        ...
        /* SPIs have restrictions on the supported types */
        if ((range == SPI_RANGE || range == ESPI_RANGE) &&
            type != IRQ_TYPE_LEVEL_HIGH && type != IRQ_TYPE_EDGE_RISING)
                return -EINVAL;
        ...
}

We have a device at hand whose interrupt type is SPI, Falling edge
will trigger the interrupt. But the request_irq(50, handler,
IRQ_TYPE_EDGE_FALLING, ...) will return -EINVAL.

The question is, why must the SPI interrupt use IRQ_TYPE_EDGE_RISING
instead of IRQ_TYPE_EDGE_FALLING?

Thanks,