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-rw-r--r--sys-kernel/boest-v5.0.15/raspberrypi/0033-amba_pl011-Insert-mb-for-correct-FIFO-handling.patch29
1 files changed, 29 insertions, 0 deletions
diff --git a/sys-kernel/boest-v5.0.15/raspberrypi/0033-amba_pl011-Insert-mb-for-correct-FIFO-handling.patch b/sys-kernel/boest-v5.0.15/raspberrypi/0033-amba_pl011-Insert-mb-for-correct-FIFO-handling.patch
new file mode 100644
index 00000000..ded891ee
--- /dev/null
+++ b/sys-kernel/boest-v5.0.15/raspberrypi/0033-amba_pl011-Insert-mb-for-correct-FIFO-handling.patch
@@ -0,0 +1,29 @@
+From ce0e3f83d941437f16242c8d87b3bf172eaadbd4 Mon Sep 17 00:00:00 2001
+From: Phil Elwell <phil@raspberrypi.org>
+Date: Fri, 29 Sep 2017 10:32:19 +0100
+Subject: [PATCH 033/194] 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(+)
+
+diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
+index 02275f96dbca..39d717e94af3 100644
+--- a/drivers/tty/serial/amba-pl011.c
++++ b/drivers/tty/serial/amba-pl011.c
+@@ -1385,6 +1385,7 @@ static bool pl011_tx_char(struct uart_amba_port *uap, unsigned char c,
+ return false; /* unable to transmit character */
+
+ pl011_write(c, uap, REG_DR);
++ mb();
+ uap->port.icount.tx++;
+
+ return true;