diff options
Diffstat (limited to 'target/linux/bcm27xx/patches-5.4/950-0033-amba_pl011-Insert-mb-for-correct-FIFO-handling.patch')
| -rw-r--r-- | target/linux/bcm27xx/patches-5.4/950-0033-amba_pl011-Insert-mb-for-correct-FIFO-handling.patch | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-5.4/950-0033-amba_pl011-Insert-mb-for-correct-FIFO-handling.patch b/target/linux/bcm27xx/patches-5.4/950-0033-amba_pl011-Insert-mb-for-correct-FIFO-handling.patch new file mode 100644 index 0000000000..f545ab1db0 --- /dev/null +++ b/target/linux/bcm27xx/patches-5.4/950-0033-amba_pl011-Insert-mb-for-correct-FIFO-handling.patch @@ -0,0 +1,27 @@ +From 37e06c9ed7219cf6cf08a0463f7e2b5b2c51f3e6 Mon Sep 17 00:00:00 2001 +From: Phil Elwell <phil@raspberrypi.org> +Date: Fri, 29 Sep 2017 10:32:19 +0100 +Subject: [PATCH] amba_pl011: Insert mb() for correct FIFO handling + +The pl011 register accessor functions use the _relaxed versions of the +standard readl() and writel() functions, meaning that there are no +automatic memory barriers. When polling a FIFO status register to check +for fullness, it is necessary to ensure that any outstanding writes have +completed; otherwise the flags are effectively stale, making it possible +that the next write is to a full FIFO. + +Signed-off-by: Phil Elwell <phil@raspberrypi.org> +--- + drivers/tty/serial/amba-pl011.c | 1 + + 1 file changed, 1 insertion(+) + +--- a/drivers/tty/serial/amba-pl011.c ++++ b/drivers/tty/serial/amba-pl011.c +@@ -1383,6 +1383,7 @@ static bool pl011_tx_char(struct uart_am + return false; /* unable to transmit character */ + + pl011_write(c, uap, REG_DR); ++ mb(); + uap->port.icount.tx++; + + return true; |