Messages in this thread | | | Subject | Re: [RFC PATCH 2/2] serial: 8250_dw: support polling mode | From | John Garry <> | Date | Mon, 26 Feb 2018 10:54:06 +0000 |
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On 23/02/2018 17:35, Andy Shevchenko wrote: > 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.
Agreed. I find the wording a bit ambigious in bindings/serial/8250.txt and snps-dw-apb-uart.txt:
Required properties: [...] - interrupts : should contain uart interrupt.
It uses the word "should", and not "must". Maybe "should" means "must"...
> >> 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");
OK
>
Thanks, John
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