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tty: serial: fsl_lpuart: Use cpu_relax() instead of barrier() 

Use cpu_relax() instead of barrier() in a tight polling loops to make
them a bit more idiomatic. Should also improve things on ARM64 a bit
since cpu_relax() will expand into "yield" instruction there.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Cory Tusar <cory.tusar@zii.aero>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-imx@nxp.com
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/r/20190729195226.8862-16-andrew.smirnov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
alistair/sunxi64-5.4-dsi
Andrey Smirnov 2019-07-29 12:52:17 -07:00 committed by Greg Kroah-Hartman
parent 56dd627fb2
commit f2f5e04c75
1 changed files with 2 additions and 2 deletions
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4
drivers/tty/serial/fsl_lpuart.c
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@ -553,14 +553,14 @@ static void lpuart_wait_bit_set(struct uart_port *port, unsigned int offset,
u8 bit)
{
while (!(readb(port->membase + offset) & bit))
barrier();
cpu_relax();
}
static void lpuart32_wait_bit_set(struct uart_port *port, unsigned int offset,
u32 bit)
{
while (!(lpuart32_read(port, offset) & bit))
barrier();
cpu_relax();
}
#if defined(CONFIG_CONSOLE_POLL)