ath5k: Optimize ath5k_cw_validate
Optimize ath5k_cw_validate by using the classic (X & (X - 1)) == 0
check to see if a number is power of 2.
v2: Use functions from log2.h instead
Signed-off-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath5k/qcu.c b/drivers/net/wireless/ath/ath5k/qcu.c
index e50e64d..30b50f9 100644
--- a/drivers/net/wireless/ath/ath5k/qcu.c
+++ b/drivers/net/wireless/ath/ath5k/qcu.c
@@ -23,6 +23,7 @@
#include "ath5k.h"
#include "reg.h"
#include "debug.h"
+#include <linux/log2.h>
/**
* DOC: Queue Control Unit (QCU)/DCF Control Unit (DCU) functions
@@ -108,13 +109,21 @@
static u16
ath5k_cw_validate(u16 cw_req)
{
- u32 cw = 1;
cw_req = min(cw_req, (u16)1023);
- while (cw < cw_req)
- cw = (cw << 1) | 1;
+ /* Check if cw_req + 1 a power of 2 */
+ if (is_power_of_2(cw_req + 1))
+ return cw_req;
- return cw;
+ /* Check if cw_req is a power of 2 */
+ if (is_power_of_2(cw_req))
+ return cw_req - 1;
+
+ /* If none of the above is correct
+ * find the closest power of 2 */
+ cw_req = (u16) roundup_pow_of_two(cw_req) - 1;
+
+ return cw_req;
}
/**