MIME-Version: 1.0
In-Reply-To: <CANfLQrbhbn9UavS1sDDhp9wZyoNQN5MdGzXhKywLJApJ8MTwWQ@mail.gmail.com>
References: <CANfLQrbhbn9UavS1sDDhp9wZyoNQN5MdGzXhKywLJApJ8MTwWQ@mail.gmail.com>
From: Gucea Doru <gucea.doru@gmail.com>
Date: Fri, 17 Feb 2017 22:57:36 +0200
Message-ID: <CANfLQrZZgghGzCzToJZF=MkMoj2bmFdj2yjFFdR7gMsAnwK1=g@mail.gmail.com> (sfid-20170217_215742_143736_EE1DAAC1)
Subject: Re: Power Save for Multi-VIF
To: linux-wireless <linux-wireless@vger.kernel.org>,
        ath9k_htc_fw@lists.infradead.org
Cc: Andra Paraschiv <andra.paraschiv7@gmail.com>,
        Costin Raiciu <costin.raiciu@cs.pub.ro>,
        Dragos N <dragos.niculescu@cs.pub.ro>
Content-Type: text/plain; charset=UTF-8
Sender: linux-wireless-owner@vger.kernel.org

On Tue, Feb 14, 2017 at 9:41 PM, Gucea Doru <gucea.doru@gmail.com> wrote:
> Hello, everyone
>
> I try to design a Power Save Algorithm in the case of a mobile client
> that has multiple virtual interfaces [1] and is connected to multiple
> Access Points simultaneously. My implementation is for the Atheros
> AR9271 WiFi chip.
>
> The biggest challenge in implementing this algorithm is waking up the
> WiFi chip for RX traffic. E.g.: the WiFi chip is in the sleep state
> and it has to wake up in order to receive beacons from all the APs
> that the client is connected to.
>
> Reading the AR9271 datasheet [2] I noticed that the chip is equipped
> with hardware timers for waking up the hardware. The registers for
> programming these hardware timers are MAC_PCU_SLP1 and MAC_PCU_SLP2.
> After the registers have been programmed, the RTC_FORCE_WAKE bit has
> to be cleared in order to allow the card to enter sleep mode (at least
> this is how is done in the existing implementation for the single VIF
> scenario).
>
> I used the logic above for programming the hardware to wake up for
> beacons from multiple APs. I used a power device for measuring the
> energy consumption and it seems that the WiFi card wakes up
> periodically to receive beacons from multiple APs. The problem is that
> after a time, out of nowhere, the WiFi card refuses to enter sleep
> mode and stays just in the awake state, although the logic for
> programming the hardware timers does not change.
>
> Could someone give more details about the FORCE_WAKE signal and what
> is the relation between this signal and the MAC and RTC layers? I
> believe that the problem comes from here. The AR9271 datasheet just
> references this signal (page 106) but it offers no details about it.

Is there any Atheros developer that could help me with a clarification
about the FORCE_WAKE signal?

Thanks,
Doru


>
> [1] https://github.com/doru91/linux-stable/wiki/Two-Interfaces-Power-Save
> [2] https://wikidevi.com/wiki/Atheros_AR9271
> [3] http://lxr.free-electrons.com/source/drivers/net/wireless/ath/ath9k/hw.c?v=4.9#L2068
>
> Regards,
> Doru