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Date:   Mon, 20 Apr 2020 15:10:59 +0300
From:   Dan Carpenter <dan.carpenter@oracle.com>
To:     Oscar Carter <oscar.carter@gmx.com>
Cc:     Forest Bond <forest@alittletooquiet.net>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        devel@driverdev.osuosl.org, Malcolm Priestley <tvboxspy@gmail.com>,
        "John B . Wyatt IV" <jbwyatt4@gmail.com>,
        linux-kernel@vger.kernel.org,
        Colin Ian King <colin.king@canonical.com>
Subject: Re: [PATCH] staging: vt6656: Use fls instead of for loop in
 vnt_update_top_rates
Message-ID: <20200420121059.GC2659@kadam>
References: <20200419100921.5421-1-oscar.carter@gmx.com>
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On Sun, Apr 19, 2020 at 12:09:21PM +0200, Oscar Carter wrote:
> -	for (i = RATE_11M;; i--) {
> -		if (priv->basic_rates & (u16)(1 << 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-- : RATE_24M;
                                          ^^^^^
Argh...  Come on.  I don't want to have to break out the C standard to
see if this is defined behavior and where the sequence points are.  A
pre-op would be clear but the most clear thing is to write it like this:

	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-- : RATE_1M;
                                         ^^^^^
Same.

regards,
dan carpenter