Re: What to set uart_port->irq to for polled driver?

[Peter Hurley <peter@hurleysoftware.com>]

On Thu, 2013-02-28 at 18:43 +0000, Grant Edwards wrote:
> On 2013-02-28, Peter Hurley <peter@hurleysoftware.com> wrote:
> > On Wed, 2013-02-13 at 15:24 +0000, Grant Edwards wrote:
> >> For a polled serial driver that doesn't use interrupts, to what should
> >> the "irq" field in the uart_port structure be set?  Should it be 0?
> >> Should it be the unused IRQ associated with the PCI card slot in which
> >> the board is found?
> >
> > Doesn't look supported, but adding the support doesn't look difficult.
> > At the very least, a patch is required so that on port shutdown, the
> > core doesn't synchronize_irq().
> 
> Does the call ty synchronize_irq() do any harm? AFAICT, it will just
> cause a short delay if handling of that IRQ is in-progress.
> 
> I currently set the "irq" field to the IRQ number that would be used
> by the board if I did choose to enable interrupts. That seems to work
> fine (with rather limited testing).

AFAICT, it's probably ok; but it might not be. Certainly more robust to
just add a UPF_POLLING flag and skip the synchronize_irq().

Is this an in-tree driver?

Regards,
Peter Hurley