From patchwork Fri Mar 13 00:06:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rasmus Villemoes X-Patchwork-Id: 243611 List-Id: U-Boot discussion From: rasmus.villemoes at prevas.dk (Rasmus Villemoes) Date: Fri, 13 Mar 2020 01:06:38 +0100 Subject: [PATCH] spi: use is_power_of_2 instead of hweight32 in spi_nor_write() Message-ID: <20200313000638.10548-1-rasmus.villemoes@prevas.dk> 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 Acked-by: Vignesh Raghavendra --- 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;