power off ath0: <Atheros AR946x/AR948x>

[Adrian Chadd]

On 12 January 2015 at 08:56, Warner Losh <imp at bsdimp.com> wrote:
>
>> On Jan 12, 2015, at 9:54 AM, John Baldwin <jhb at FreeBSD.org> wrote:
>>
>> On 1/11/15 3:05 AM, Matthias Apitz wrote:
>>>
>>> Hello,
>>>
>>> Is there a way to completely power-off the Wifi chip in my Acer C720?
>>> I tried 'ifconfig ath0 down' which saves around 20 mA. But the LED stays
>>> on, which let me think it is still someow on-air.
>>
>> Not yet.  You could try setting the tunable to disable power for PCI
>> devices without a driver and not include 'ath' in your kernel config.  I
>> will (soon) commit a new 'devctl' tool to HEAD that would let you do
>> 'devctl suspend ath0' to do this.
>
> I’d love to see this tied into the forthcoming work on PCIe hot plug as well,
> which is one way to power off the slot. But that work seems to be stalled…

Right. So, the driver in -HEAD should be powering off almost all of
the chip when no vap (ie, wlanX) is active. The only parts of the chip
that stay on is the PCIe PHY and the GPIO/RTC block. AFAIK we don't
support PCIe power save state management at the moment, so we can't
keep the PCIe PHY off.

But yeah, most of the chip is off. The chip doesn't take all that much
power unless it's actively transmitting/receiving. The LEDs are on
because the GPIO block is on and it's likely holding the LED up.



-adrian