Commit 983fe58a authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
Browse files

serial: atmel_serial: drop low-latency workaround 



Commit 1ecc26bd ("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 a9c3f68f ("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 <richard.genoud@gmail.com>
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-10-johan@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e9af7e36

drivers/tty/serial/atmel_serial.c

+0 −18
Original line number Diff line number Diff line
@@ -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);