Re: [PATCH v2 4/7] serial: 8250: Handle implementations not having TEMT interrupt using em485

[Andy Shevchenko]

On Thu, Mar 26, 2020 at 12:14:19AM +0100, Heiko Stuebner wrote:
> From: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxx>
> 
> Some 8250 ports have a TEMT interrupt but it's not a part of the 8250
> standard, instead only available on some implementations.
> 
> The current em485 implementation does not work on ports without it.
> The only chance to make it work is to loop-read on LSR register.
> 
> So add UART_CAP_TEMT to mark 8250 uarts having this interrupt,
> update all current em485 users with that capability and make
> the stop_tx function loop-read on uarts not having it.

> +		if (p->capabilities & UART_CAP_TEMT) {
> +			if ((lsr & BOTH_EMPTY) != BOTH_EMPTY)
> +				return;
> +		} else {
> +			int lsr;
> +

> +			if (readx_poll_timeout(__get_lsr, p, lsr,
> +					(lsr & BOTH_EMPTY) == BOTH_EMPTY,
> +					0, 10000) < 0)

			ret = readx_poll_timeout(...);
			if (ret)
				...

will look better.

> +				pr_warn("%s: timeout waiting for fifos to empty\n",
> +					p->port.name);
> +		}

-- 
With Best Regards,
Andy Shevchenko