linux-kernel - [PATCH 15/26] serial: mpc52xx_uart: drop low-latency workaround

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Date:   Wed, 21 Apr 2021 11:54:58 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Jiri Slaby <jirislaby@...nel.org>, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>
Subject: [PATCH 15/26] serial: mpc52xx_uart: drop low-latency workaround

Commit fbe543b412ce ("Fix a potential issue in mpc52xx uart driver")
worked around the infamous low_latency behaviour of
tty_flip_buffer_push() by simply dropping and reacquiring the port lock
in the interrupt handler.

Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.

Signed-off-by: Johan Hovold <johan@...nel.org>
---
 drivers/tty/serial/mpc52xx_uart.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/tty/serial/mpc52xx_uart.c b/drivers/tty/serial/mpc52xx_uart.c
index af1700445251..2704dc988e4a 100644
--- a/drivers/tty/serial/mpc52xx_uart.c
+++ b/drivers/tty/serial/mpc52xx_uart.c
@@ -1421,9 +1421,7 @@ mpc52xx_uart_int_rx_chars(struct uart_port *port)
 		}
 	}

-	spin_unlock(&port->lock);
 	tty_flip_buffer_push(tport);
-	spin_lock(&port->lock);

 	return psc_ops->raw_rx_rdy(port);
 }
-- 
2.26.3