Re: [PATCH 1/2] p54: implement multicast filter

[Max Filippov <jcmvbkbc@gmail.com>]

> "For best CPU usage and power consumption, having as few
> frames as possible percolate through the stack is
> desirable. Hence, the hardware should filter as much
> as possible."
> 
> Note: Not all firmwares include the multicast filter
> feature and the stack does not filter them either.
> The ARP filter on the other hand was dropped from the
> patch since it does not work correctly:
> 
> Quote from: Max Filippov <jcmvbkbc@gmail.com>
> <http://www.spinics.net/lists/linux-wireless/msg67466.html>
> "In the ARP case, when there's no other traffic on p54spi,
> all ARP requests are dropped. But if there's some egress
> traffic from p54spi, filter seems to work correctly:
> only ARP requests that match filter pass through.
> 
> In the multicast case filter seems to work correctly, but
> it treats broadcast as subject to that filtering too. By
> default only 01:00:5e:00:00:01 gets into priv->mc_maclist,
> so we miss all broadcasts.
> 
> These two filters seem to interfere:
> - if we set ARP filter and multicast filter without bc
> 	=>  we miss all ARPs if there's no egress traffic;
> - if we set ARP filter and multicast filter with bc or
> 	don't set mc filter at all => we get all ARPs.
> 
> This effect does not depend on filter setup order."
> 
> Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>

wrt p54spi:

Tested-by: Max Filippov <jcmvbkbc@gmail.com>

Thanks.
-- Max