Subject: Re: [PATCH RFC 1/2] net: dsa: integrate with SWITCHDEV for HW bridging

From: Florian Fainelli <[email-masked]>
Date: Tue, 17 Feb 2015 12:24:26 -0800

On 17/02/15 12:13, Guenter Roeck wrote:
> On 02/17/2015 11:26 AM, Florian Fainelli wrote:
>> In order to support bridging offloads in DSA switch drivers, select
>> NET_SWITCHDEV to get access to the port_stp_update and parent_get_id
>> NDOs that we are required to implement.
>>
>> To facilitate the integratation at the DSA driver level, we implement 3
>> types of operations:
>>
>> - port_join_bridge
>> - port_leave_bridge
>> - port_stp_update
>>
>> DSA will resolve which switch ports that are currently bridge port
>> members as some Switch hardware/drivers need to know about that to limit
>> the register programming to just the relevant registers (especially for
>> slow MDIO buses).
>>
>> Signed-off-by: Florian Fainelli <[email-masked]>
>> ---
>>   include/net/dsa.h  |  10 +++++
>>   net/dsa/Kconfig    |   1 +
>>   net/dsa/dsa.c      |   7 ++++
>>   net/dsa/dsa_priv.h |   2 +
>>   net/dsa/slave.c    | 117
>> +++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   5 files changed, 137 insertions(+)
>>
>> diff --git a/include/net/dsa.h b/include/net/dsa.h
>> index ed3c34bbb67a..92be34791963 100644
>> --- a/include/net/dsa.h
>> +++ b/include/net/dsa.h
>> @@ -275,6 +275,16 @@ struct dsa_switch_driver {
>>       int    (*get_regs_len)(struct dsa_switch *ds, int port);
>>       void    (*get_regs)(struct dsa_switch *ds, int port,
>>                   struct ethtool_regs *regs, void *p);
>> +
>> +    /*
>> +     * Bridge integration
>> +     */
>> +    int    (*port_join_bridge)(struct dsa_switch *ds, int port,
>> +                    u32 br_port_mask);
>> +    int    (*port_leave_bridge)(struct dsa_switch *ds, int port,
>> +                     u32 br_port_mask);
>> +    int    (*port_stp_update)(struct dsa_switch *ds, int port,
>> +                   u8 state);
>>   };
>>
>>   void register_switch_driver(struct dsa_switch_driver *type);
>> diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
>> index 5f8ac404535b..b45206e8dd3e 100644
>> --- a/net/dsa/Kconfig
>> +++ b/net/dsa/Kconfig
>> @@ -8,6 +8,7 @@ config NET_DSA
>>       tristate
>>       depends on HAVE_NET_DSA
>>       select PHYLIB
>> +    select NET_SWITCHDEV
> 
> Should this be "select" or "depends on" ?
> 
> Downside of depends is that we'll need some ifdefs in the code,
> but on the other side it would let people disable it if it is
> not needed.

The code overhead is not huge, and I would think that by enforcing
NET_SWITCHDEV we encourage better DSA driver practices and promote HW
bridging, if you think this should be made conditional, I guess we can
do that.
-- 
Florian