From d3fbd457013c0f6d96de461ce0a9cb1f8b73cd0b Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Fri, 10 Jan 2014 17:09:53 +0000 Subject: [PATCH] spi: Use bitfields for multiple data lines Trent Piepho observed that since the current realistic maximum number of data lines is four we can pack the spi_transfer struct more efficiently if we use a bitfield for the number of bits, allowing the fields to fit in a single byte along with cs_change. If space becomes an issue further optimiation is possible by only using the constants and packing the values chosen for them. Reported-by: Trent Piepho Signed-off-by: Mark Brown --- include/linux/spi/spi.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 27a882978c15..77b529e418d5 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -576,8 +576,8 @@ struct spi_transfer { dma_addr_t rx_dma; unsigned cs_change:1; - u8 tx_nbits; - u8 rx_nbits; + unsigned tx_nbits:3; + unsigned rx_nbits:3; #define SPI_NBITS_SINGLE 0x01 /* 1bit transfer */ #define SPI_NBITS_DUAL 0x02 /* 2bits transfer */ #define SPI_NBITS_QUAD 0x04 /* 4bits transfer */ -- 2.30.2