b9b2a76a43
According to comments in linux/spi/spi.h: * All SPI transfers start with the relevant chipselect active. Normally * it stays selected until after the last transfer in a message. Drivers * can affect the chipselect signal using cs_change. * * (i) If the transfer isn't the last one in the message, this flag is * used to make the chipselect briefly go inactive in the middle of the * message. Toggling chipselect in this way may be needed to terminate * a chip command, letting a single spi_message perform all of group of * chip transactions together. * * (ii) When the transfer is the last one in the message, the chip may * stay selected until the next transfer. On multi-device SPI busses * with nothing blocking messages going to other devices, this is just * a performance hint; starting a message to another device deselects * this one. But in other cases, this can be used to ensure correctness. * Some devices need protocol transactions to be built from a series of * spi_message submissions, where the content of one message is determined * by the results of previous messages and where the whole transaction * ends when the chipselect goes intactive. Signed-off-by: Yi Li <yi.li@analog.com> Signed-off-by: Bryan Wu <cooloney@kernel.org> Acked-by: David Brownell <dbrownell@users.sourceforge.net> Cc: David Brownell <david-b@pacbell.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| .. | ||
| atmel_spi.c | ||
| atmel_spi.h | ||
| au1550_spi.c | ||
| Kconfig | ||
| Makefile | ||
| mpc52xx_psc_spi.c | ||
| omap2_mcspi.c | ||
| omap_uwire.c | ||
| orion_spi.c | ||
| pxa2xx_spi.c | ||
| spi.c | ||
| spi_bfin5xx.c | ||
| spi_bitbang.c | ||
| spi_butterfly.c | ||
| spi_gpio.c | ||
| spi_imx.c | ||
| spi_lm70llp.c | ||
| spi_mpc83xx.c | ||
| spi_s3c24xx.c | ||
| spi_s3c24xx_gpio.c | ||
| spi_sh_sci.c | ||
| spi_txx9.c | ||
| spidev.c | ||
| tle62x0.c | ||
| xilinx_spi.c | ||