Using relaxed IO accessors allows GCC to better optimise this code
as we eliminate the heavy memory barriers - for example, GCC can now
cache the address of a register across a read-modify-write sequence,
rather than reloading the base address, offset and access size flag.
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
---
drivers/tty/serial/amba-pl011.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 54c6c88a71a3..a7d7ab05dc64 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -262,7 +262,7 @@ static unsigned int pl011_read(const struct uart_amba_port *uap,
{
void __iomem *addr = uap->port.membase + pl011_reg_to_offset(uap, reg);
- return uap->access_32b ? readl(addr) : readw(addr);
+ return uap->access_32b ? readl_relaxed(addr) : readw_relaxed(addr);
}
static void pl011_write(unsigned int val, const struct uart_amba_port *uap,
@@ -271,9 +271,9 @@ static void pl011_write(unsigned int val, const struct uart_amba_port *uap,
void __iomem *addr = uap->port.membase + pl011_reg_to_offset(uap, reg);
if (uap->access_32b)
- writel(val, addr);
+ writel_relaxed(val, addr);
else
- writew(val, addr);
+ writew_relaxed(val, addr);
}
/*
--
2.1.0
--
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