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| author |   Johan Hovold <johan@kernel.org> | 2021-04-21 11:54:48 +0200 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-04-22 12:09:24 +0200 |
| commit | 02d5364007ba95eb3c90ba5710e3ccbdf6c56cfb (patch) | |
| tree | 93d6b00fa23c4d0e881fcf8a1d68b010f4392109 /drivers/tty/serial/amba-pl011.c | |
| parent | serial: amba-pl010: drop low-latency workaround (diff) | |
| download | wireguard-linux-02d5364007ba95eb3c90ba5710e3ccbdf6c56cfb.tar.xz wireguard-linux-02d5364007ba95eb3c90ba5710e3ccbdf6c56cfb.zip | |
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 <linus.walleij@linaro.org>
Cc: Russell King <linux@armlinux.org.uk>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-6-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/amba-pl011.c')
| -rw-r--r-- | drivers/tty/serial/amba-pl011.c | 2 |
1 files changed, 0 insertions, 2 deletions
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) |