Re: [PATCH tty-next v3 2/6] serial: 8250: Use high-level write function for FIFO

From: Andy Shevchenko
Date: Fri Oct 25 2024 - 09:51:22 EST


On Fri, Oct 25, 2024 at 01:03:24PM +0206, John Ogness wrote:
> Currently serial8250_console_fifo_write() directly writes into the
> UART_TX register, rather than using the high-level function
> serial8250_console_putchar(). This is because
> serial8250_console_putchar() waits for the holding register to
> become empty. That would defeat the purpose of the FIFO code.

You can slightly reformat the above to make it less shaky in terms
of the efficiency of a line capacity usage.

Currently serial8250_console_fifo_write() directly writes into
the UART_TX register, rather than using the high-level function
serial8250_console_putchar(). This is because
serial8250_console_putchar() waits for the holding register
to become empty. That would defeat the purpose of the FIFO code.

> Move the LSR_THRE waiting to a new function
> serial8250_console_wait_putchar() so that the FIFO code can use
> serial8250_console_putchar(). This will be particularly important
> for a follow-up commit, where output bytes are inspected to track
> newlines.

> This is only refactoring and has no functional change.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

--
With Best Regards,
Andy Shevchenko