In case of error, the function devm_ioremap_resource() returns ERR_PTR()
and never returns NULL. The NULL test in the return value check should be
replaced with IS_ERR().
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
Current code keeps the clocks enabled all the time, it wastes the power
when there is no operaiton on the spi controller.
In order to save the power, this patch adds the two hooks:
spi_imx_prepare_message: enable the clocks for this message
spi_imx_unprepare_message: disable the clocks.
This patch also disables the clocks in the end of the probe.
Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
mxs_spi_setup_transfer() would set the SSP SCK rate every time it was
called, which is before every transfer. It is uncommon for the SCK rate to
change between transfers (or at all of that matter) and this causes many
unnecessary reprogrammings of the clock registers.
Code changed to only set the rate when it changes. This significantly
speeds up short SPI messages, especially messages made up of many transfers,
as the calculation of the clock divisors is rather costly. On an iMX287,
using spidev with messages that consist of 511 transfers of 4 bytes each at
an SCK of 48 MHz, the effective transfer rate more than doubles from about
290 KB/sec to 600 KB/sec!
Signed-off-by: Trent Piepho <tpiepho@gmail.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>
Mark Brown
Kuninori Morimoto
Wei Yongjun
Huang Shijie
Trent Piepho