From 02d5364007ba95eb3c90ba5710e3ccbdf6c56cfb Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Wed, 21 Apr 2021 11:54:48 +0200 Subject: serial: amba-pl011: drop low-latency workaround Commit ead76f329f77 ("ARM: 6763/1: pl011: add optional RX DMA to PL011 v2") added RX DMA support and also reproduced the workaround for the infamous low_latency behaviour of tty_flip_buffer_push() by dropping and reacquiring the port lock during receive processing. 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. Note that the port lock is also dropped in the PIO path (see pl011_rx_chars), but it is not clear whether this is still needed by the DMA code added by the aforementioned commit. Cc: Linus Walleij Cc: Russell King Reviewed-by: Linus Walleij Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20210421095509.3024-6-johan@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/amba-pl011.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 4ead0c9048a8..78682c12156a 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -937,12 +937,10 @@ static void pl011_dma_rx_chars(struct uart_amba_port *uap, fifotaken = pl011_fifo_to_tty(uap); } - spin_unlock(&uap->port.lock); dev_vdbg(uap->port.dev, "Took %d chars from DMA buffer and %d chars from the FIFO\n", dma_count, fifotaken); tty_flip_buffer_push(port); - spin_lock(&uap->port.lock); } static void pl011_dma_rx_irq(struct uart_amba_port *uap) -- cgit v1.2.3