linux-kernel - [PATCH v2 0/3] serial: 8250: Set fifo timeout with uart_fifo

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Date: Tue, 16 Apr 2024 18:28:41 +0000
From: Michael Pratt <mcpratt@...me>
To: linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jirislaby@...nel.org>
Cc: Wander Lairson Costa <wander@...hat.com>, Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Vamshi Gajjela <vamshigajjela@...gle.com>, Michael Pratt <mcpratt@...me>
Subject: [PATCH v2 0/3] serial: 8250: Set fifo timeout with uart_fifo_timeout()

Hi all,

On Thu, Jan 11, 2024 I submitted a single patch solution
for this issue of data overrun because of the default timeout
value which is insufficient for very low baud rates
with the internal fifo device enabled.

Following the advice of Vamshi Gajjela in the v1 thread,
I tried to find a way to limit the amount of math
being done within the write operation, and this is a possibility.

In this series, I'm proposing we bring back the
"timeout" member of struct uart_port, and also that we
add a new member of struct uart_8250_port in order
to store whether the fifo device has been enabled.

This way, in the function wait_for_lsr()
all we need to do is convert the value from jiffies to usecs
in order to have the appropriate timeout value.

I'm hoping to get this in during the RC phase of v6.9
and I'm trying to keep this fix as simple as possible,
or at least I think this is the appropriate time to
bring this issue up again...

Thanks in advance for your time.

--
MCP

Michael Pratt (3):
  serial: core: Store fifo timeout again
  serial: 8250: Store whether fifo device is enabled
  serial: 8250: Set fifo timeout using uart_fifo_timeout()

 drivers/tty/serial/8250/8250_port.c | 7 ++++++-
 drivers/tty/serial/serial_core.c    | 3 +++
 include/linux/serial_8250.h         | 1 +
 include/linux/serial_core.h         | 1 +
 4 files changed, 11 insertions(+), 1 deletion(-)

base-commit: 0bbac3facb5d6cc0171c45c9873a2dc96bea9680
--
2.30.2