28 lines
1014 B
Diff
28 lines
1014 B
Diff
From 29a82b892694e27f1537a84a0d1dfa163dd51af8 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
|
|
@@ -1456,6 +1456,7 @@ 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;
|