Le 06/12/2016 à 20:01, Marek Vasut a écrit : > On 12/06/2016 05:01 PM, Cyrille Pitchen wrote: >> The patch checks whether the Quad Enable bit is already set in the Status >> Register. If so, the function exits immediately with a successful return >> code. > > Performance optimization I presume ?
Performance optimization is one benefit but this real purpose of the patch is to avoid writing over and over a non-volatile bit at each boot, actually each time spi_nor_scan() is called. To be honest, I don't know whether internally the SPI memory is clever enough not to perform the actual write when it sees the bit value has not changed. I wanted to improve the memory lifetime by avoiding the update of the bit from software just to be sure :) Anyway, thanks for your review! > > Acked-by: Marek Vasut <[email protected]> > >> Signed-off-by: Cyrille Pitchen <[email protected]> >> Reviewed-by: Jagan Teki <[email protected]> >> --- >> drivers/mtd/spi-nor/spi-nor.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c >> index da7cd69d4857..1fd32b991eb7 100644 >> --- a/drivers/mtd/spi-nor/spi-nor.c >> +++ b/drivers/mtd/spi-nor/spi-nor.c >> @@ -1216,6 +1216,9 @@ static int macronix_quad_enable(struct spi_nor *nor) >> val = read_sr(nor); >> if (val < 0) >> return val; >> + if (val & SR_QUAD_EN_MX) >> + return 0; >> + >> write_enable(nor); >> >> write_sr(nor, val | SR_QUAD_EN_MX); >> > >
