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spi: use is_power_of_2 instead of hweight32 in spi_nor_write() 

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>
Acked-by: Jagan Teki <jagan@amarulasolutions.com>
This commit is contained in:
Rasmus Villemoes 2020-03-13 01:06:38 +01:00 committed by Jagan Teki
parent 91afd36f38
commit 7ddea75654
1 changed files with 1 additions and 4 deletions
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5
drivers/mtd/spi/spi-nor-core.c
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@ -1246,11 +1246,8 @@ 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 * If page_size is a power of two, the offset can be quickly
* calculated with an AND operation. On the other cases we * calculated with an AND operation. On the other cases we
* need to do a modulus operation (more expensive). * 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); page_offset = addr & (nor->page_size - 1);
} else { } else {
u64 aux = addr; u64 aux = addr;