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28 lines
1022 B
Diff
28 lines
1022 B
Diff
From 436e9b301802720c0bf0f080301263c6e926d723 Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Fri, 29 Sep 2017 10:32:19 +0100
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Subject: [PATCH 121/454] amba_pl011: Insert mb() for correct FIFO handling
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The pl011 register accessor functions use the _relaxed versions of the
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standard readl() and writel() functions, meaning that there are no
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automatic memory barriers. When polling a FIFO status register to check
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for fullness, it is necessary to ensure that any outstanding writes have
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completed; otherwise the flags are effectively stale, making it possible
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that the next write is to a full FIFO.
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Signed-off-by: Phil Elwell <phil@raspberrypi.org>
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---
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drivers/tty/serial/amba-pl011.c | 1 +
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1 file changed, 1 insertion(+)
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--- a/drivers/tty/serial/amba-pl011.c
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+++ b/drivers/tty/serial/amba-pl011.c
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@@ -1401,6 +1401,7 @@ static bool pl011_tx_char(struct uart_am
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return false; /* unable to transmit character */
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pl011_write(c, uap, REG_DR);
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+ mb();
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uap->port.icount.tx++;
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return true;
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