netdev - Re: [PATCH net-next] net: dsa: mv88e6xxx: debug ATU Age Time

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Date:   Mon, 13 Mar 2017 23:39:32 +0100
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>,
        Jason Cobham <jcobham@...stertangent.com>
Subject: Re: [PATCH net-next] net: dsa: mv88e6xxx: debug ATU Age Time

On Mon, Mar 13, 2017 at 03:20:43PM -0400, Vivien Didelot wrote:
> The ATU ageing time value programmed in the switch is rounded up to the
> nearest multiple of its coefficient (variable depending on the model.)
> 
> Add a debug message to inform the user about the exact programmed value.
> 
> On 6352, "brctl setageing br0 18" gives "AgeTime set to 0x01 (15000 ms)"
> while on 6390 we get "AgeTime set to 0x05 (18750 ms)".
> 
> Signed-off-by: Vivien Didelot <vivien.didelot@...oirfairelinux.com>
> ---
>  drivers/net/dsa/mv88e6xxx/global1_atu.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/dsa/mv88e6xxx/global1_atu.c b/drivers/net/dsa/mv88e6xxx/global1_atu.c
> index f6cd3c939da4..bac34737b096 100644
> --- a/drivers/net/dsa/mv88e6xxx/global1_atu.c
> +++ b/drivers/net/dsa/mv88e6xxx/global1_atu.c
> @@ -65,7 +65,14 @@ int mv88e6xxx_g1_atu_set_age_time(struct mv88e6xxx_chip *chip,
>  	val &= ~0xff0;
>  	val |= age_time << 4;
>  
> -	return mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
> +	err = mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
> +	if (err)
> +		return err;
> +
> +	dev_dbg(chip->dev, "AgeTime set to 0x%02x (%d ms)\n", age_time,
> +		age_time * coeff);
> +

Hi Vivien

You could put the dev_dbg before the mv88e6xxx_g1_write(), to keep the
code simpler. If this write fails, we expect a lot of other things to
go horribly wrong, so having one debug message being not quite accurate
is not important.

   Andrew