Hi, On 13/03/20 5:36 am, Rasmus Villemoes wrote: > hweight32 is a somewhat expensive way to check for power-of-2. Use the > is_power_of_2 helper, which does the standard and cheap idiom > foo&(foo-1)==0. > > add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-96 (-96) > Function old new delta > spi_nor_write 388 292 -96 > > Signed-off-by: Rasmus Villemoes <[email protected]>
Acked-by: Vignesh Raghavendra <[email protected]> > --- > drivers/mtd/spi/spi-nor-core.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c > index eb49a6c11c..4076646225 100644 > --- a/drivers/mtd/spi/spi-nor-core.c > +++ b/drivers/mtd/spi/spi-nor-core.c > @@ -1240,11 +1240,8 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t > to, size_t len, > * If page_size is a power of two, the offset can be quickly > * calculated with an AND operation. On the other cases we > * need to do a modulus operation (more expensive). > - * Power of two numbers have only one bit set and we can use > - * the instruction hweight32 to detect if we need to do a > - * modulus (do_div()) or not. > */ > - if (hweight32(nor->page_size) == 1) { > + if (is_power_of_2(nor->page_size)) { > page_offset = addr & (nor->page_size - 1); > } else { > u64 aux = addr; > -- Regards Vignesh
