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From: Gucea Doru <gucea.doru@gmail.com>
To: Arend van Spriel <arend@broadcom.com>
Cc: Andra Paraschiv <andra.paraschiv7@gmail.com>,
	linux-wireless@vger.kernel.org
Subject: bcmdhd: Strange Power Save messages
Date: Tue, 27 Sep 2016 12:03:35 +0300	[thread overview]
Message-ID: <CANfLQrY6AVJoh8PW+5Ev0seKqnNRxRhK-N735q6Aa4KvdUVEcg@mail.gmail.com> (raw)

Hello,

I am analyzing the Power Save algorithm used on a pair of Nexus 5
devices. The devices use the bcmdhd Broadcom driver and are Wi-Fi
Direct connected.

My test is very simple: I send ping packets from the P2P client
towards the P2P GO. Before sending a ping packet the P2P client enters
PS mode (it sends a Null frame with the PWR MGT bit set). A few
miliseconds later, the P2P client sends the ping request message. Once
the ping request is ACKed the P2P client exits the PS mode (it sends a
Null frame with the PWR MGT bit unset) and the P2P GO decides to send
him the ping reply.

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.

For reference, the Wireshark trace can be found at [1].
SSID: DIRECT-35-Android_Intel
WPA pass: JYdrhZp3

[1] https://drive.google.com/file/d/0B5SBH08PU_ChQk95LWpzekh3VU0/view?usp=sharing

Thank you,
Doru

             reply	other threads:[~2016-09-27  9:03 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-27  9:03 Gucea Doru [this message]
2016-09-29 11:32 ` bcmdhd: Strange Power Save messages Gucea Doru
2016-10-01  9:22   ` Arend van Spriel
2016-10-01 12:02     ` Krishna Chaitanya
2016-10-04 11:39       ` Gucea Doru
2016-10-04 12:37         ` Krishna Chaitanya
2016-10-04 18:27           ` Gucea Doru
2016-10-04 18:54             ` Krishna Chaitanya
2016-10-05  9:12         ` Arend Van Spriel
2016-10-06  8:07           ` Gucea Doru
2016-10-06  8:25             ` Arend Van Spriel
2016-10-07 14:33               ` Gucea Doru
2016-10-11 19:12                 ` Arend van Spriel
2016-10-12 14:26                   ` Gucea Doru
2016-10-12 18:48                     ` Arend van Spriel

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