atmel_spi: work-around required for new HW bug in AT91SAM9263 Rev.B SPI controller

atmel_spi: work-around required for new HW bug in AT91SAM9263 Rev.B SPI controller

We're working with an AT91SAM9263 Rev B in our design and I experienced
some inconsistency in spi-based touchscreen usage between our board and
the Atmel evaluation kit we have that runs on a Rev A chip.

The data was apparently delayed by 1 byte and got ridiculous data out of
the touchscreen driver, very strange.  As everything looked normal in
the spi, touchscreen and dma logs, I contacted the Atmel support and
they triggered me on a new HW bug that appeared in the Rev B SPI
controller.

The problem is that the SPI controller on the Rev B needs that the
software reset is performed two times so that it's performed correctly.

Applying the patch below solves the issue on my Rev B board.  I've tested
it as well on my Rev A evaluation kit and it has apparently no unwanted
side effect, things continue to work as expected.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
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>