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authorNed Forrester <nforrester@whoi.edu>2008-02-23 15:23:40 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-23 17:12:14 -0800
commitb97c74bddce4e2c6fef6b3b58910b4fd9eb7f3b8 (patch)
tree36e48f2687ba0c54350f740da796f321c7d2500c /mm
parentf6febccd7f86fbe94858a4a32d9384cc014c9f40 (diff)
spi: pxa2xx_spi clock polarity fix
Fixes a sequencing bug in spi driver pxa2xx_spi.c in which the chip select for a transfer may be asserted before the clock polarity is set on the interface. As a result of this bug, the clock signal may have the wrong polarity at transfer start, so it may need to make an extra half transition before the intended clock/data signals begin. (This probably means all transfers are one bit out of sequence.) This only occurs on the first transfer following a change in clock polarity in systems using more than one more than one such polarity. The fix assures that the clock mode is properly set before asserting chip select. This bug was introduced in a patch merged on 2006/12/10, kernel 2.6.20. The patch defines an additional bit in: include/asm-arm/arch-pxa/regs-ssp.h for 2.6.25 and newer kernels but this addition must be made in: include/asm-arm/arch-pxa/pxa-regs.h for kernels between 2.6.20 and 2.6.24, inclusive Signed-off-by: Ned Forrester <nforrester@whoi.edu> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Cc: Russell King <rmk@arm.linux.org.uk> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
0 files changed, 0 insertions, 0 deletions