On 07-10-16 16:33, Gucea Doru wrote: > On Thu, Oct 6, 2016 at 10:25 AM, Arend Van Spriel > <arend.vanspriel@xxxxxxxxxxxx> wrote: >> On 6-10-2016 10:07, Gucea Doru wrote: >>> On Wed, Oct 5, 2016 at 11:12 AM, Arend Van Spriel >>> <arend.vanspriel@xxxxxxxxxxxx> wrote: >>>> On 4-10-2016 13:39, Gucea Doru wrote: >>>>> On Sat, Oct 1, 2016 at 2:52 PM, Arend van Spriel >>>>>> <arend.vanspriel@xxxxxxxxxxxx> wrote: >>>>>>> >>>>>>> >>>>>>> On 29-09-16 13:32, Gucea Doru wrote: >>>>>>>> On Tue, Sep 27, 2016 at 12:03 PM, Gucea Doru <gucea.doru@xxxxxxxxx> wrote: >>>>>>>>> What is the decision triggering the exit from the PS mode immediately >>>>>>>>> after the ping request? I am asking this because 802.11 PS legacy >>>>>>>>> specifies that the client should wait for a beacon with TIM set in >>>>>>>>> order to wake up: in my case, there is no beacon between the ping >>>>>>>>> request message and the Null frame that announces the exit from the PS >>>>>>>>> mode. >>>>>>>> >>>>>>>> >>>>>>>> Any help would be highly appreciated :) >>>>>>> >>>>>>> Actually though I already sent you are reply, but alas here it is. >>>>>>> >>>>>>> bcmdhd is our aosp driver. I am maintaining the upstream brcm80211 >>>>>>> drivers. Regardless your question is more for firmware running on the >>>>>>> device. So like the same behavior would be observed when using brcmfmac >>>>>>> with same firmware. >>>>>>> >>>>>>>> IEEE Std 802.11-2012, section 10.2.1.8 specifies that "when the STA >>>>>>>> detects that the bit corresponding to its AID is 1 i the TIM, the STA >>>>>>>> shall issue a PS Poll". In my capture there are cases when the STA >>>>>>>> exits the PS mode without waiting for a beacon. >>>>>>> >>>>>>> It is a bit tricky, but the standard does not explicitly say the STA >>>>>>> should be in power-save at any other time. So it is difficult to say >>>>>>> what event occurred on the STA side to exit PS mode. Also STA means >>>>>>> P2P-Client as you say. That means that you have multiple interfaces: >>>>>>> regular STA and P2P-Client. So is the STA connected to some other AP or >>>>>>> just not connected. wpa_supplicant will do intermittent scan or initiate >>>>>>> scheduled scan by which firmware will scan at a certain interval. That >>>>>>> is just some things I can come up with and I am sure there are more. >>>>> >>>>> I agree that there may be some events belonging to the regular STA >>>>> interface that could trigger the Null Frame (which includes the exit >>>>> from PS Mode). However, I would expect to see some management frames >>>>> in the air before/after the Null Packet (e.g.: a Probe request in case >>>>> of a scheduled scan). But in my case the trigger for the Null frame >>>>> seems to be the ping request packet, the scenario is the same every >>>>> time: ping request -> Block ACK -> Null Frame (Wireshark trace >>>>> confirms this behavior). >>>>> >>>>> I thought that you had a power save optimization algorithm that keeps >>>>> the card on a few milliseconds just to see if we can have a fast reply >>>>> from the peer. Does this ring a bell? :) >>>> >>>> It does not. That would be implemented in firmware. As said I am working >>>> on brcmfmac/brcmsmac. So bcmdhd and firmware are not my expertise. >>>> >>> >>> Arend, could you please redirect me to a Broadcom firmware maintainer? >> >> Can you please elaborate on your platform, broadcom chipset, and what >> version of bcmdhd you are using. >> > > Platform: Nexus 5 running CM13 (Android 6.0.1) > Broadcom chipset: BCM4339 Wi-Fi Chipset > bcmdhd version:Dongle Host Driver, version 1.88.45 (r) > > Do you need more information? So can you indicate the mac addresses of the two nexus devices and which one is P2P-GO. I entered the wpa key you mentioned in your initial email, but my wireshark does not seem to be able to decrypt the packets, which makes it a bit harder to analyze. Regards, Arend
