0ff2de8bb1
For some SPI devices that support speed_hz > 1MHz the default 10 us delay
when cs_change = 1 is typically way to long and may result in poor spi bus
utilization.
This patch makes it possible to control the delay at micro or nano second
resolution on a per spi_transfer basis. It even allows an "as fast as
possible" mode with:
xfer.cs_change_delay_unit = SPI_DELAY_UNIT_NSECS;
xfer.cs_change_delay = 0;
The delay code is shared between delay_usecs and cs_change_delay for
consistency and reuse, so in the future this change_delay_unit could also
apply to delay_usec as well.
Note that on slower SOCs/CPU actually reaching ns deasserts on cs is not
realistic as the gpio overhead alone (without any delays added ) may
already leave cs deasserted for more than 1us - at least on a raspberry pi.
But at the very least this way we can keep it as short as possible.
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
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| .. | ||
| ad7877.h | ||
| ads7846.h | ||
| at73c213.h | ||
| at86rf230.h | ||
| cc2520.h | ||
| corgi_lcd.h | ||
| ds1305.h | ||
| eeprom.h | ||
| flash.h | ||
| ifx_modem.h | ||
| l4f00242t03.h | ||
| libertas_spi.h | ||
| lms283gf05.h | ||
| max7301.h | ||
| mc33880.h | ||
| mcp23s08.h | ||
| mmc_spi.h | ||
| mxs-spi.h | ||
| pxa2xx_spi.h | ||
| rspi.h | ||
| s3c24xx.h | ||
| sh_hspi.h | ||
| sh_msiof.h | ||
| spi-fsl-dspi.h | ||
| spi-mem.h | ||
| spi.h | ||
| spi_bitbang.h | ||
| spi_gpio.h | ||
| spi_oc_tiny.h | ||
| tdo24m.h | ||
| tle62x0.h | ||
| xilinx_spi.h | ||