From f6c0485c509e21dee309595646eb4d0dcd38ac07 Mon Sep 17 00:00:00 2001 From: Alexander Shiyan Date: Wed, 19 Dec 2018 14:19:20 +0300 Subject: [PATCH] serial: max310x: Fix tx_empty() callback [ Upstream commit a8da3c7873ea57acb8f9cea58c0af477522965aa ] Function max310x_tx_empty() accesses the IRQSTS register, which is cleared by IC when reading, so if there is an interrupt status, we will lose it. This patch implement the transmitter check only by the current FIFO level. Signed-off-by: Alexander Shiyan Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/max310x.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c index bacc7e284c0c..80ab672d61cc 100644 --- a/drivers/tty/serial/max310x.c +++ b/drivers/tty/serial/max310x.c @@ -769,12 +769,9 @@ static void max310x_start_tx(struct uart_port *port) static unsigned int max310x_tx_empty(struct uart_port *port) { - unsigned int lvl, sts; + u8 lvl = max310x_port_read(port, MAX310X_TXFIFOLVL_REG); - lvl = max310x_port_read(port, MAX310X_TXFIFOLVL_REG); - sts = max310x_port_read(port, MAX310X_IRQSTS_REG); - - return ((sts & MAX310X_IRQ_TXEMPTY_BIT) && !lvl) ? TIOCSER_TEMT : 0; + return lvl ? 0 : TIOCSER_TEMT; } static unsigned int max310x_get_mctrl(struct uart_port *port)