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authorJohan Hovold <johan@kernel.org>2021-04-21 12:54:48 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-04-22 13:09:24 +0300
commit02d5364007ba95eb3c90ba5710e3ccbdf6c56cfb (patch)
tree93d6b00fa23c4d0e881fcf8a1d68b010f4392109 /drivers/tty
parent173d37fc598a2c2cfc73288203a1154557c810be (diff)
downloadlinux-02d5364007ba95eb3c90ba5710e3ccbdf6c56cfb.tar.xz
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')
-rw-r--r--drivers/tty/serial/amba-pl011.c2
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)