tree 857d8c03baab8c845cd94cd601caab05e57dcb5b
parent 3c72426f0539c1abce17918d1456f7a6a5a11f90
author Haavard Skinnemoen <hskinnemoen@atmel.com> 1202290691 -0800
committer Linus Torvalds <torvalds@woody.linux-foundation.org> 1202323270 -0800

atmel_spi throughput improvement

Don't insert (undesirable) delays between consecutive words (DLYBCT) or when
activating chipselects (DLYBS).

Removing the between-word delays improves the performance of bulk transfers
(such as mtd_dataflash, m25p80, mmc_spi) significantly.  In one test, the
improvement was a factor of more than eight!

(The large DLYBCT value came from the legacy at91 SPI driver, and it's not
clear why it used such a huge value.)

Signed-off-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>