diff options
| author | Daniel Thompson <daniel.thompson@linaro.org> | 2014-06-18 11:27:14 +0100 |
|---|---|---|
| committer | Daniel Thompson <daniel.thompson@linaro.org> | 2014-09-03 12:58:43 +0100 |
| commit | 7956ac13424c5aa8f15c65cfd177e04a540f0414 (patch) | |
| tree | 631c24bc185f8133349c5e1a887747aa3d7a144c | |
| parent | 8d656f055800a15a6723af1f4782d93180d40350 (diff) | |
| download | linux-dev/st-asc-relaxed.tar.gz | |
serial: asc: Adopt readl_/writel_relaxed()dev/st-asc-relaxed
The architectures where this peripheral exists (ARM and SH) have expensive
implementations of writel(), reliant on spin locks and explicit L2 cache
management. These architectures provide a cheaper writel_relaxed() which
is much better suited to peripherals that do not perform DMA. The
situation with readl()/readl_relaxed()is similar although less acute.
This driver does not use DMA and will be more power efficient and more
robust (due to absense of spin locks during console I/O) if it uses the
relaxed variants.
This change means the driver is no longer portable and therefore no
longer suitable for compile testing.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@gmail.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: kernel@stlinux.com
Cc: linux-serial@vger.kernel.org
Acked-by: Maxime Coquelin <maxime.coquelin@st.com>
Acked-by: Peter Griffin <peter.griffin@linaro.org>
| -rw-r--r-- | drivers/tty/serial/Kconfig | 2 | ||||
| -rw-r--r-- | drivers/tty/serial/st-asc.c | 4 |
2 files changed, 3 insertions, 3 deletions
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index 26cec64dadd7..e9b1735145d4 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -1527,7 +1527,7 @@ config SERIAL_FSL_LPUART_CONSOLE config SERIAL_ST_ASC tristate "ST ASC serial port support" select SERIAL_CORE - depends on ARM || COMPILE_TEST + depends on ARM help This driver is for the on-chip Asychronous Serial Controller on STMicroelectronics STi SoCs. diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c index 8b2d7356611d..adadbc17b082 100644 --- a/drivers/tty/serial/st-asc.c +++ b/drivers/tty/serial/st-asc.c @@ -151,12 +151,12 @@ static inline struct asc_port *to_asc_port(struct uart_port *port) static inline u32 asc_in(struct uart_port *port, u32 offset) { - return readl(port->membase + offset); + return readl_relaxed(port->membase + offset); } static inline void asc_out(struct uart_port *port, u32 offset, u32 value) { - writel(value, port->membase + offset); + writel_relaxed(value, port->membase + offset); } /* |