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154443c72f
Add support for chained transfers in the atmel_spi driver, letting the DMA
controller switch to the next buffer pair without CPU intervention. This
reduced I/O latencies by about 2% in one bulk I/O test. It should also help
work around several interrelated errata affecting chipselect 0 on at91rm9200
chips.
Almost all of the changes are in the reworked atmel_spi_next_xfer() function.
That's now called with the driver in one of three states:
1. It isn't transferring anything (in which case the first transfer
of the current message is going to be sent)
2. It has finished transfering a non-chainable transfer (in which
case it will go to the next transfer in the message)
3. It has finished transfering a chained transfer (in which case the
next transfer is already queued)
After that it will queue the next transfer if it can be chained.
Signed-off-by: Szilveszter Ordog <slipszi@gmail.com>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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| .. | ||
| at25.c | ||
| atmel_spi.c | ||
| atmel_spi.h | ||
| au1550_spi.c | ||
| Kconfig | ||
| Makefile | ||
| mpc52xx_psc_spi.c | ||
| omap2_mcspi.c | ||
| omap_uwire.c | ||
| pxa2xx_spi.c | ||
| spi.c | ||
| spi_bfin5xx.c | ||
| spi_bitbang.c | ||
| spi_butterfly.c | ||
| spi_imx.c | ||
| spi_lm70llp.c | ||
| spi_mpc83xx.c | ||
| spi_s3c24xx.c | ||
| spi_s3c24xx_gpio.c | ||
| spi_txx9.c | ||
| spidev.c | ||
| tle62x0.c | ||
| xilinx_spi.c | ||