linux-kernel - [PATCH 21/26] serial: txx9: drop low-latency workaround

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Message-Id: <20210421095509.3024-22-johan@kernel.org>
Date:   Wed, 21 Apr 2021 11:55:04 +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 21/26] serial: txx9: drop low-latency workaround

Commit f5ee56cc184e ("[PATCH] txx9 serial update") 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/serial_txx9.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/serial_txx9.c b/drivers/tty/serial/serial_txx9.c
index 7a07e7272de1..0a7e5b74bc1d 100644
--- a/drivers/tty/serial/serial_txx9.c
+++ b/drivers/tty/serial/serial_txx9.c
@@ -330,9 +330,9 @@ receive_chars(struct uart_txx9_port *up, unsigned int *status)
 		up->port.ignore_status_mask = next_ignore_status_mask;
 		disr = sio_in(up, TXX9_SIDISR);
 	} while (!(disr & TXX9_SIDISR_UVALID) && (max_count-- > 0));
-	spin_unlock(&up->port.lock);
+
 	tty_flip_buffer_push(&up->port.state->port);
-	spin_lock(&up->port.lock);
+
 	*status = disr;
 }
 
-- 
2.26.3