Re: [PATCH v2 3/3] serial: 8250: Set fifo timeout using uart_fifo_timeout()

[Michael Pratt]

Hi Andy,

On Tuesday, April 16th, 2024 at 14:57, Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:

> 
> > unsigned int status, tmout = 10000;
> > 
> > - /* Wait up to 10ms for the character(s) to be sent. /
> > + / Wait for a time relative to buffer size and baud */
> > + if (up->fifo_enable && up->port.timeout)
> > + tmout = jiffies_to_usecs(up->port.timeout);
> 
> 
> Why do we still use that default? Can't we calculate timeout even for\
> FIFO-less / FIFO-disabled devices?

Maybe it's possible that there is some kind of rare case where the LSR register
is not working or not configured properly for a device in which support
is being worked on...without a timeout, that would result in an infinite loop.

AFAIK, when everything is working properly, there is no such thing as needing
a timeout for a uart device without fifo, as every single byte written would trigger
an interrupt anyway.

> --
> With Best Regards,
> Andy Shevchenko

--
MCP