Re: [PATCH tty-next v4 1/6] serial: 8250: Adjust the timeout for FIFO mode

[Petr Mladek <pmladek@suse.com>]

On Fri 2024-12-27 23:51:17, John Ogness wrote:
> After a console has written a record into UART_TX, it uses
> wait_for_xmitr() to wait until the data has been sent out before
> returning. However, wait_for_xmitr() will timeout after 10ms,
> regardless if the data has been transmitted or not.
> 
> For single bytes, this timeout is sufficient even at very slow
> baud rates, such as 1200bps. However, when FIFO mode is used,
> there may be 64 bytes pushed into the FIFO at once. At a baud
> rate of 115200bps, the 10ms timeout is still sufficient. But
> when using lower baud rates (such as 57600bps), the timeout
> is _not_ sufficient. This causes longer lines to be cut off,
> resulting in lost and horribly misformatted output on the
> console.
> 
> When using FIFO mode, take the number of bytes into account to
> determine an appropriate maximum timeout. Increasing the timeout
> does not affect performance since ideally the timeout never
> occurs.
> 
> Fixes: 8f3631f0f6eb ("serial/8250: Use fifo in 8250 console driver")
> Signed-off-by: John Ogness <john.ogness@linutronix.de>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Reviewed-by: Wander Lairson Costa <wander@redhat.com>

Looks good to me:

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr