RE: [PATCH] wifi: rtl8xxxu: Fix off by one initial RTS rate

[Ping-Ke Shih <pkshih@realtek.com>]

> -----Original Message-----
> From: Bitterblue Smith <rtl8821cerfe2@gmail.com>
> Sent: Monday, January 1, 2024 6:19 AM
> To: linux-wireless@vger.kernel.org
> Cc: Jes Sorensen <Jes.Sorensen@gmail.com>; Ping-Ke Shih <pkshih@realtek.com>
> Subject: [PATCH] wifi: rtl8xxxu: Fix off by one initial RTS rate
> 
> rtl8xxxu_set_basic_rates() sets the wrong initial RTS rate. It sets the
> next higher rate than the one it should set, e.g. 36M instead of 24M.
> 
> The while loop is supposed to find the index of the most significant
> bit which is 1.
> 
> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
> ---
>  drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> index 180907319e8c..b9f3382bd67c 100644
> --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> @@ -4839,7 +4839,7 @@ static void rtl8xxxu_set_basic_rates(struct rtl8xxxu_priv *priv, u32 rate_cfg)
> 
>         dev_dbg(&priv->udev->dev, "%s: rates %08x\n", __func__, rate_cfg);
> 
> -       while (rate_cfg) {
> +       while (rate_cfg > 1) {
>                 rate_cfg = (rate_cfg >> 1);
>                 rate_idx++;
>         }

How about using __fls()? 

if (rate_cfg)
	rate_idx = __fls(rate_cfg);

> --
> 2.43.0