P2P Device support: how to deal with p2p_no_group_iface option

Arend van Spriel arend at broadcom.com
Mon May 27 09:56:19 EDT 2013

On 05/27/2013 11:03 AM, Johannes Berg wrote:
> Hi,
>> I looked into issues around hwsim p2p tests and got all but one p2p test
>> passing now (test_autogo_tdls). I had to remove the p2p_no_group_iface
>> option from the p2px.conf files, because otherwise it tries to change
>> the P2P management interface into a P2P group interface. When using
>> P2P_DEVICE and P2P management interface this is not allowed by
>> mac80211_hwsim. Also for brcmfmac the P2P_DEVICE interface is dedicated
>> and can only be added/deleted, but not changed. Not sure if that is true
>> for iwlmvm as well.
>> So I would like to discuss how to deal with the p2p_no_group_iface
>> option. As P2P_DEVICE is a new concept the name of the option may no
>> longer match what it intends. Is the option to force all P2P operations
>> to be done on a single interface, ie. wlan0 (or whatever is specified on
>> the command line) and no P2P_DEVICE is to be created. Or should it
>> change the interface from the command line as P2P group interface.
> I don't think I'd do either of those. Not creating P2P_DEVICE will
> simply not work with drivers expecting it, and changing iftype to/from
> P2P-Device isn't supported since it would delete/create the netdev.

So should we check that in cfg80211 upon wiphy_register().

> I don't really see much choice but reject (or ignore) this option for
> drivers using P2P_DEVICE. Why would anyone *really* want P2P operation
> on wlan0 when another interface can be used?

In this mac80211_hwsim is a special case. We could make P2P_DEVICE 
support in mac80211_hwsim optional using module parameter to allow 
testing both cases.


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