On Tue, Feb 14, 2017 at 9:41 PM, Gucea Doru <gucea.doru@xxxxxxxxx> 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
