From 372b49ba0775d1a0b577198ce501481bf989d7d7 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 8 Jun 2022 12:54:31 +0300 Subject: [PATCH] serial: 8250_dw: Store LSR into lsr_saved_flags in dw8250_tx_wait_empty() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit [ Upstream commit af14f3007e2dca0d112f10f6717ba43093f74e81 ] Make sure LSR flags are preserved in dw8250_tx_wait_empty(). This function is called from a low-level out function and therefore cannot call serial_lsr_in() as it would lead to infinite recursion. It is borderline if the flags need to be saved here at all since this code relates to writing LCR register which usually implies no important characters should be arriving. Fixes: 914eaf935ec7 ("serial: 8250_dw: Allow TX FIFO to drain before writing to UART_LCR") Reviewed-by: Andy Shevchenko Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20220608095431.18376-7-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/8250/8250_dw.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index 4955973..ace221a 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -124,12 +124,15 @@ static void dw8250_check_lcr(struct uart_port *p, int value) /* Returns once the transmitter is empty or we run out of retries */ static void dw8250_tx_wait_empty(struct uart_port *p) { + struct uart_8250_port *up = up_to_u8250p(p); unsigned int tries = 20000; unsigned int delay_threshold = tries - 1000; unsigned int lsr; while (tries--) { lsr = readb (p->membase + (UART_LSR << p->regshift)); + up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; + if (lsr & UART_LSR_TEMT) break; -- 2.7.4