netdev - Re: [PATCH net] net: dsa: mv88e6xxx: fix few issues in mv88e6390x_port_set

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Date:   Wed, 27 Mar 2019 22:38:24 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        David Miller <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net] net: dsa: mv88e6xxx: fix few issues in
 mv88e6390x_port_set_cmode

On 27.03.2019 22:22, Florian Fainelli wrote:
> On 3/23/19 11:41 AM, Heiner Kallweit wrote:
>> This patches fixes few issues in mv88e6390x_port_set_cmode().
>>
>> 1. When entering the function the old cmode may be 0, in this case
>>    mv88e6390x_serdes_get_lane() returns -ENODEV. As result we bail
>>    out and have no chance to set a new mode. Therefore deal properly
>>    with -ENODEV.
>>
>> 2. Once we have disabled power and irq, let's set the cached cmode to 0.
>>    This reflects the actual status and is cleaner if we bail out with an
>>    error in the following function calls.
>>
>> 3. The cached cmode is used by mv88e6390x_serdes_get_lane(),
>>    mv88e6390_serdes_power_lane() and mv88e6390_serdes_irq_enable().
>>    Currently we set the cached mode to the new one at the very end of
>>    the function only, means until then we use the old one what may be
>>    wrong.
>>
>> 4. When calling mv88e6390_serdes_irq_enable() we use the lane value
>>    belonging to the old cmode. Get the lane belonging to the new cmode
>>    before calling this function.
>>
>> It's hard to provide a good "Fixes" tag because quite a few smaller
>> changes have been done to the code in question recently.
>>
>> Fixes: d235c48b40d3 ("net: dsa: mv88e6xxx: power serdes on/off for 10G interfaces on 6390X")
>> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
>> ---
>>  drivers/net/dsa/mv88e6xxx/port.c | 24 ++++++++++++++++--------
>>  1 file changed, 16 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/net/dsa/mv88e6xxx/port.c b/drivers/net/dsa/mv88e6xxx/port.c
>> index dce84a2a6..c44b2822e 100644
>> --- a/drivers/net/dsa/mv88e6xxx/port.c
>> +++ b/drivers/net/dsa/mv88e6xxx/port.c
>> @@ -427,18 +427,22 @@ int mv88e6390x_port_set_cmode(struct mv88e6xxx_chip *chip, int port,
>>  		return 0;
>>  
>>  	lane = mv88e6390x_serdes_get_lane(chip, port);
>> -	if (lane < 0)
>> +	if (lane < 0 && lane != -ENODEV)
>>  		return lane;
> 
> It does not look like you can return a negative error code from
> mv88e6390x_serdes_get_lane() that is not -ENODEV?
> 
Thanks for reviewing, Florian. Right, at least for now
mv88e6390x_serdes_get_lane() doesn't return any other errno.
But that's not carved in stone, and if somebody comes and adds
a check that returns -EINVAL to this function, then this person
most likely won't update mv88e6390x_port_set_cmode().

> Other than that:
> 
> Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
>