From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.thompson@linaro.org (Daniel Thompson) Date: Tue, 19 Aug 2014 17:46:07 +0100 Subject: [PATCH v10 17/19] serial: asc: Adopt readl_/writel_relaxed() In-Reply-To: <1408466769-20004-1-git-send-email-daniel.thompson@linaro.org> References: <1408369264-14242-1-git-send-email-daniel.thompson@linaro.org> <1408466769-20004-1-git-send-email-daniel.thompson@linaro.org> Message-ID: <1408466769-20004-18-git-send-email-daniel.thompson@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 Cc: Srinivas Kandagatla Cc: Maxime Coquelin Cc: Patrice Chotard Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: kernel at stlinux.com Cc: linux-serial at vger.kernel.org --- drivers/tty/serial/Kconfig | 2 +- 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 26cec64..e9b1735 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 2b5eb6e..df709ee 100644 --- a/drivers/tty/serial/st-asc.c +++ b/drivers/tty/serial/st-asc.c @@ -152,12 +152,12 @@ 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); } /* -- 1.9.3