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Commit f5ce6edd authored by Russell King's avatar Russell King Committed by Greg Kroah-Hartman
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tty: amba-pl011: switch to using relaxed IO accessors 



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: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7ec75871

drivers/tty/serial/amba-pl011.c

+3 −3
Original line number Diff line number Diff line
@@ -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);

}



/*