From 983fe58ad72d45e5c12eb8166dc85657065dd34e Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Wed, 21 Apr 2021 11:54:52 +0200 Subject: [PATCH] serial: atmel_serial: drop low-latency workaround Commit 1ecc26bd2789 ("atmel_serial: split the interrupt handler") worked around the infamous low_latency behaviour of tty_flip_buffer_push() by dropping and reacquiring the port lock in the tasklet callback. 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. Cc: Richard Genoud Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20210421095509.3024-10-johan@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/atmel_serial.c | 18 ------------------ 1 file changed, 18 deletions(-) diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index a24e5c2b30bc..058886d9045b 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -1178,13 +1178,7 @@ static void atmel_rx_from_dma(struct uart_port *port) 1, DMA_FROM_DEVICE); - /* - * Drop the lock here since it might end up calling - * uart_start(), which takes the lock. - */ - spin_unlock(&port->lock); tty_flip_buffer_push(tport); - spin_lock(&port->lock); atmel_uart_writel(port, ATMEL_US_IER, ATMEL_US_TIMEOUT); } @@ -1576,13 +1570,7 @@ static void atmel_rx_from_ring(struct uart_port *port) uart_insert_char(port, status, ATMEL_US_OVRE, c.ch, flg); } - /* - * Drop the lock here since it might end up calling - * uart_start(), which takes the lock. - */ - spin_unlock(&port->lock); tty_flip_buffer_push(&port->state->port); - spin_lock(&port->lock); } static void atmel_release_rx_pdc(struct uart_port *port) @@ -1667,13 +1655,7 @@ static void atmel_rx_from_pdc(struct uart_port *port) } } while (head >= pdc->dma_size); - /* - * Drop the lock here since it might end up calling - * uart_start(), which takes the lock. - */ - spin_unlock(&port->lock); tty_flip_buffer_push(tport); - spin_lock(&port->lock); atmel_uart_writel(port, ATMEL_US_IER, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT); -- 2.11.0