linux-kernel - [PATCH v2] staging: vt6656: Use fls instead of for loop in vnt_update_top

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Message-Id: <20200420155246.4925-1-oscar.carter@gmx.com>
Date:   Mon, 20 Apr 2020 17:52:46 +0200
From:   Oscar Carter <oscar.carter@....com>
To:     Forest Bond <forest@...ttletooquiet.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Dan Carpenter <dan.carpenter@...cle.com>,
        Malcolm Priestley <tvboxspy@...il.com>,
        Oscar Carter <oscar.carter@....com>,
        Quentin Deslandes <quentin.deslandes@...ev.co.uk>,
        "John B . Wyatt IV" <jbwyatt4@...il.com>,
        Colin Ian King <colin.king@...onical.com>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] staging: vt6656: Use fls instead of for loop in vnt_update_top_rates

Replace the for loops of the vnt_update_top_rates function by the fls
function.

The purpose of the two for loops is to find the most significant bit set
in a range of bits. So, they can be replace by the fls function (find
last set) with a previous mask to define the range.

This way avoid the iteration over unnecessary for loops.

The header "linux/bits.h" can be remove as it is included in the header
"linux/bitops.h".

Signed-off-by: Oscar Carter <oscar.carter@....com>
---
Changelog v1 -> v2
- Replace the expression pos-- with the expresion (pos - 1) as Dan
  Carpenter suggested.

 drivers/staging/vt6656/card.c | 28 ++++++----------------------
 1 file changed, 6 insertions(+), 22 deletions(-)

diff --git a/drivers/staging/vt6656/card.c b/drivers/staging/vt6656/card.c
index f8bfadd4b506..2478edee756a 100644
--- a/drivers/staging/vt6656/card.c
+++ b/drivers/staging/vt6656/card.c
@@ -26,7 +26,7 @@
  *
  */

-#include <linux/bits.h>
+#include <linux/bitops.h>
 #include "device.h"
 #include "card.h"
 #include "baseband.h"
@@ -223,29 +223,13 @@ void vnt_update_ifs(struct vnt_private *priv)

 void vnt_update_top_rates(struct vnt_private *priv)
 {
-	u8 top_ofdm = RATE_24M, top_cck = RATE_1M;
-	u8 i;
+	int pos;

-	/*Determines the highest basic rate.*/
-	for (i = RATE_54M; i >= RATE_6M; i--) {
-		if (priv->basic_rates & BIT(i)) {
-			top_ofdm = i;
-			break;
-		}
-	}
-
-	priv->top_ofdm_basic_rate = top_ofdm;
-
-	for (i = RATE_11M;; i--) {
-		if (priv->basic_rates & BIT(i)) {
-			top_cck = i;
-			break;
-		}
-		if (i == RATE_1M)
-			break;
-	}
+	pos = fls(priv->basic_rates & GENMASK(RATE_54M, RATE_6M));
+	priv->top_ofdm_basic_rate = pos ? (pos - 1) : RATE_24M;

-	priv->top_cck_basic_rate = top_cck;
+	pos = fls(priv->basic_rates & GENMASK(RATE_11M, RATE_1M));
+	priv->top_cck_basic_rate = pos ? (pos - 1) : RATE_1M;
 }

 int vnt_ofdm_min_rate(struct vnt_private *priv)
--
2.20.1