diff options
authorDaniel Thompson <daniel.thompson@linaro.org>2014-06-18 11:27:14 +0100
committerDaniel Thompson <daniel.thompson@linaro.org>2014-09-03 12:58:43 +0100
commit7956ac13424c5aa8f15c65cfd177e04a540f0414 (patch)
parent8d656f055800a15a6723af1f4782d93180d40350 (diff)
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>
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
tristate "ST ASC serial port support"
- depends on ARM || COMPILE_TEST
+ depends on ARM
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);