linux-kernel - Re: [PATCH net-next v3 11/12] net: dsa: mv88e6xxx: add G1 helper for ageing time

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Message-ID: <20160719144518.GC31103@lunn.ch>
Date:	Tue, 19 Jul 2016 16:45:18 +0200
From:	Andrew Lunn <andrew@...n.ch>
To:	Vivien Didelot <vivien.didelot@...oirfairelinux.com>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel@...oirfairelinux.com,
	"David S. Miller" <davem@...emloft.net>,
	Florian Fainelli <f.fainelli@...il.com>
Subject: Re: [PATCH net-next v3 11/12] net: dsa: mv88e6xxx: add G1 helper for
 ageing time

> +static int mv88e6xxx_g1_set_age_time(struct mv88e6xxx_chip *chip,
> +				     unsigned int msecs)
> +{
> +	const unsigned int coeff = chip->info->age_time_coeff;
> +	const unsigned int min = 0x01 * coeff;
> +	const unsigned int max = 0xff * coeff;
> +	u8 age_time;
> +	u16 val;
> +	int err;
> +
> +	if (msecs < min || msecs > max)
> +		return -ERANGE;
> +
> +	/* Round to nearest multiple of coeff */
> +	age_time = (msecs + coeff / 2) / coeff;
> +
> +	err = mv88e6xxx_read(chip, REG_GLOBAL, GLOBAL_ATU_CONTROL, &val);
> +	if (err)
> +		return err;
> +
> +	/* AgeTime is 11:4 bits */
> +	val &= ~0xff0;
> +	val |= age_time << 4;
> +
> +	return mv88e6xxx_write(chip, REG_GLOBAL, GLOBAL_ATU_CONTROL, val);
> +}

Hi Vivien

This is doing a read/modify/write, so should really hold the mutex.

> +	err = mv88e6xxx_g1_set_age_time(chip, 300000);

Maybe use (5 * 60 * 1000) to make it more readable?

      Andrew