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 rasmus.villemoes@prevas.dk

Acked-by: Vignesh Raghavendra vigneshr@ti.com

---

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;