From b97c74bddce4e2c6fef6b3b58910b4fd9eb7f3b8 Mon Sep 17 00:00:00 2001 From: Ned Forrester Date: Sat, 23 Feb 2008 15:23:40 -0800 Subject: 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 Signed-off-by: David Brownell Cc: Russell King Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-arm/arch-pxa/regs-ssp.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/asm-arm/arch-pxa/regs-ssp.h') diff --git a/include/asm-arm/arch-pxa/regs-ssp.h b/include/asm-arm/arch-pxa/regs-ssp.h index 991cb688db7..0255328c3c1 100644 --- a/include/asm-arm/arch-pxa/regs-ssp.h +++ b/include/asm-arm/arch-pxa/regs-ssp.h @@ -85,6 +85,7 @@ #define SSCR1_RSRE (1 << 20) /* Receive Service Request Enable */ #define SSCR1_TINTE (1 << 19) /* Receiver Time-out Interrupt enable */ #define SSCR1_PINTE (1 << 18) /* Peripheral Trailing Byte Interupt Enable */ +#define SSCR1_IFS (1 << 16) /* Invert Frame Signal */ #define SSCR1_STRF (1 << 15) /* Select FIFO or EFWR */ #define SSCR1_EFWR (1 << 14) /* Enable FIFO Write/Read */ -- cgit v1.2.3