From: Mark Brown broonie@linaro.org
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 tpiepho@gmail.com Signed-off-by: Mark Brown broonie@linaro.org --- 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 */