[PATCH 1/2] platform/x86: dell-laptop: Use fns() in kbd_led_level_set()

[Yury Norov <ynorov@nvidia.com>]

Replace the loop clearing lower set bits with fns() to select the
supported token corresponding to the requested brightness. Preserve the
zero return when the requested index is out of range.

Signed-off-by: Yury Norov <ynorov@nvidia.com>
---
 drivers/platform/x86/dell/dell-laptop.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-laptop.c b/drivers/platform/x86/dell/dell-laptop.c
index 89e85c7f7132..03d3bb70b0d1 100644
--- a/drivers/platform/x86/dell/dell-laptop.c
+++ b/drivers/platform/x86/dell/dell-laptop.c
@@ -17,6 +17,7 @@
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/backlight.h>
+#include <linux/bitops.h>
 #include <linux/err.h>
 #include <linux/dmi.h>
 #include <linux/io.h>
@@ -2036,7 +2037,7 @@ static int kbd_led_level_set(struct led_classdev *led_cdev,
 	enum led_brightness new_value = value;
 	struct kbd_state state;
 	struct kbd_state new_state;
-	u16 num;
+	unsigned int bit;
 	int ret;
 
 	mutex_lock(&kbd_led_mutex);
@@ -2051,12 +2052,8 @@ static int kbd_led_level_set(struct led_classdev *led_cdev,
 			goto out;
 		ret = kbd_set_state_safe(&new_state, &state);
 	} else if (kbd_get_valid_token_counts()) {
-		for (num = kbd_token_bits; num != 0 && value > 0; --value)
-			num &= num - 1; /* clear the first bit set */
-		if (num == 0)
-			ret = 0;
-		else
-			ret = kbd_set_token_bit(ffs(num) - 1);
+		bit = fns(kbd_token_bits, value);
+		ret = bit == BITS_PER_LONG ? 0 : kbd_set_token_bit(bit);
 	} else {
 		pr_warn("Keyboard brightness level control not supported\n");
 		ret = -ENXIO;
-- 
2.53.0