From: John Ogness Date: Tue, 7 Jan 2025 21:26:58 +0000 (+0106) Subject: serial: 8250: Use frame time to determine timeout X-Git-Tag: v6.14-rc1~59^2~15 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=8d5cfb1fe5d8692b2de79b3831445be982167531;p=linux-block.git serial: 8250: Use frame time to determine timeout Rather than using a hard-coded per-character Tx-timeout of 10ms, use the frame time to determine a timeout value. The value is doubled to ensure that a timeout is only hit during unexpected circumstances. Since the frame time may not be available during early printing, the previous 10ms value is kept as a fallback. Signed-off-by: John Ogness Reviewed-by: Petr Mladek Link: https://lore.kernel.org/r/20250107212702.169493-3-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 3a946ebe9139..ca8f6f3855eb 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2081,9 +2081,17 @@ static void serial8250_break_ctl(struct uart_port *port, int break_state) /* Returns true if @bits were set, false on timeout */ static bool wait_for_lsr(struct uart_8250_port *up, int bits) { - unsigned int status, tmout = 10000; + unsigned int status, tmout; + + /* + * Wait for a character to be sent. Fallback to a safe default + * timeout value if @frame_time is not available. + */ + if (up->port.frame_time) + tmout = up->port.frame_time * 2 / NSEC_PER_USEC; + else + tmout = 10000; - /* Wait up to 10ms for the character(s) to be sent. */ for (;;) { status = serial_lsr_in(up);