Re: [RFC PATCH 2/2] serial: 8250_dw: support polling mode

Andy Shevchenko
2018-02-23T17:35:18Z

On Fri, 2018-02-23 at 02:42 +0800, John Garry wrote:
> It would be useful to make this driver support some
> 8250-compatible devices which have no interrupt line.
>
> For these, we allow for no interrupt, and will fallback on
> polling mode.
>
> Note: the 8250 dt bindings state that "interrupts"
> is a required property:
> "interrupts : should contain uart interrupt."
>
> But the 8250_of.c driver can live without it. So
> this patch is going this way also.

It should be documented in the binding.

> if (irq < 0) {
> - if (irq != -EPROBE_DEFER)
> - dev_err(dev, "cannot get irq\n");
> - return irq;
> + if (irq == -EPROBE_DEFER)
> + return irq;
> + dev_warn(dev, "cannot get irq, using polling
> mode\n");
> + irq = 0;

NO_IRQ _is_ 0. You need to do something like

if (irq < 0) }
... leave existing code ...
}

if (!irq)
dev_warn(, "Use polling mode\n");

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