Re: [PATCH linux-next v2 3/4] tty/serial: at91: add support to FIFOs

From: Alexandre Belloni
Date: Thu Jun 18 2015 - 12:36:52 EST


Hi,

On 11/06/2015 at 18:20:16 +0200, Cyrille Pitchen wrote :
>
> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>

Seems good to me, a few comments:

> + if (port->fifo_size < 8 || port->fifo_size > 32) {

I'm not sure why you limit the size to 32. At some point, a new SoC may
be release with a bigger FIFO then we'll have to change the code instead
of just putting the appropriate value in the device tree.

> + port->fifo_size = 0;
> + dev_err(&pdev->dev, "Invalid FIFO size\n");
> + return;
> + }
> +
> + /*
> + * 0 <= rts_low <= rts_high <= fifo_size
> + * Once their CTS line asserted by the remote peer, some x86 UARTs tend
> + * to flush their internal TX FIFO, commonly up to 8 data, before
> + * actually stopping to send new data. So we try to set the RTS High
> + * Threshold to a raisonable high value respecting this 8 data empirical
reasonably --^

--
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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