netdev - Re: [PATCH v2 12/13] net: ethernet: ti: cpts: calc mult and shift from refclk freq

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Message-ID: <20161129103453.GJ3110@localhost.localdomain>
Date:   Tue, 29 Nov 2016 11:34:53 +0100
From:   Richard Cochran <richardcochran@...il.com>
To:     Grygorii Strashko <grygorii.strashko@...com>
Cc:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Mugunthan V N <mugunthanvnm@...com>,
        Sekhar Nori <nsekhar@...com>, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        devicetree@...r.kernel.org, Murali Karicheri <m-karicheri2@...com>,
        Wingman Kwok <w-kwok2@...com>,
        John Stultz <john.stultz@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH  v2 12/13] net: ethernet: ti: cpts: calc mult and shift
 from refclk freq

On Mon, Nov 28, 2016 at 05:03:36PM -0600, Grygorii Strashko wrote:
> +static void cpts_calc_mult_shift(struct cpts *cpts)
> +{
> +	u64 frac, maxsec, ns;
> +	u32 freq, mult, shift;
> +
> +	freq = clk_get_rate(cpts->refclk);
> +
> +	/* Calc the maximum number of seconds which we can run before
> +	 * wrapping around.
> +	 */
> +	maxsec = cpts->cc.mask;
> +	do_div(maxsec, freq);
> +	if (maxsec > 600 && cpts->cc.mask > UINT_MAX)
> +		maxsec = 600;

The reason for this test is not obvious.  Why check cc.mask against
UINT_MAX?  Please use the comment to explain it.

Thanks,
Richard