atmel_spi throughput improvement

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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>

...

This commit is contained in:

Haavard Skinnemoen 2008-02-06 01:38:11 -08:00 • committed by Linus Torvalds

parent 3c72426f05

commit 1eed29df47

1 changed files with 8 additions and 3 deletions

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drivers/spi/atmel_spi.c

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