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Lockheed

Member

Registered: 2010-03-16

Posts: 1,550

Can't enable power saving for WiFi card

No matter what I do, there seem to be no way to enable power saving on my Intel 4965 wifi card. Even powertop is unable to switch it's to power level
and the file

 /sys/bus/pci/drivers/iwl4965/*/power_level

doesn't exist.

Last edited by Lockheed (2012-02-18 09:11:50)

Avant-texte

Member

Registered: 2012-02-13

Posts: 136

Re: Can't enable power saving for WiFi card

Wi-Fi power management can be enabled by adding the following line:

iwconfig wlan0 power on

to/etc/rc.local (change wlan0to whatever your wireless interface is named). If it does not work, you may also need to create the following empty file/etc/pm/power.d/wireless .

Did you try this?

Lockheed

Member

Registered: 2010-03-16

Posts: 1,550

Re: Can't enable power saving for WiFi card

Wi-Fi power management can be enabled by adding the following line:

iwconfig wlan0 power on

to/etc/rc.local (change wlan0to whatever your wireless interface is named). If it does not work, you may also need to create the following empty file/etc/pm/power.d/wireless .

Did you try this?

$ sudo iwconfig wlan0 power on
Password: 
Error for wireless request "Set Power Management" (8B2C) :
    SET failed on device wlan0 ; Operation not supported.

Lockheed

Member

Registered: 2010-03-16

Posts: 1,550

Re: Can't enable power saving for WiFi card

Here is some more information on my wifi card:

Network controller: Intel Corporation PRO/Wireless 4965 AG or AGN [Kedron] Network Connection (rev 61)
	Subsystem: Intel Corporation Lenovo ThinkPad T61
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR+ <PERR- INTx-
	Latency: 0, Cache Line Size: 64 bytes
	Interrupt: pin A routed to IRQ 49
	Region 0: Memory at df2fe000 (64-bit, non-prefetchable) [size=8K]
	Capabilities: <access denied>
	Kernel driver in use: iwl4965

newtonelectron

Member

Registered: 2012-03-29

Posts: 30

Re: Can't enable power saving for WiFi card

Same exact problem. I do power saving the old fasioned way. Just turn it off when not using it. But a fix would be nice.

Network Connection (rev 61)
	Subsystem: Intel Corporation Vaio VGN-SZ79SN_C
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 45
	Region 0: Memory at d4400000 (64-bit, non-prefetchable) [size=8K]
	Capabilities: [c8] Power Management version 3
		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [d0] MSI: Enable+ Count=1/1 Maskable- 64bit+
		Address: 00000000fee0100c  Data: 4191
	Capabilities: [e0] Express (v1) Endpoint, MSI 00
		DevCap:	MaxPayload 128 bytes, PhantFunc 0, Latency L0s <512ns, L1 unlimited
			ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
		DevCtl:	Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
			RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+
			MaxPayload 128 bytes, MaxReadReq 128 bytes
		DevSta:	CorrErr+ UncorrErr- FatalErr- UnsuppReq+ AuxPwr+ TransPend-
		LnkCap:	Port #0, Speed 2.5GT/s, Width x1, ASPM L0s L1, Latency L0 <128ns, L1 <64us
			ClockPM+ Surprise- LLActRep- BwNot-
		LnkCtl:	ASPM L1 Enabled; RCB 64 bytes Disabled- Retrain- CommClk+
			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed 2.5GT/s, Width x1, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
	Capabilities: [100 v1] Advanced Error Reporting
		UESta:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UEMsk:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UESvrt:	DLP+ SDES- TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
		CESta:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
		CEMsk:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
		AERCap:	First Error Pointer: 00, GenCap- CGenEn- ChkCap- ChkEn-
	Capabilities: [140 v1] Device Serial Number xx-x1-xx-xx-xx-xx-xx-xx
	Kernel driver in use: iwl4965

Last edited by newtonelectron (2012-03-29 04:44:44)

newtonelectron

Member

Registered: 2012-03-29

Posts: 30

Re: Can't enable power saving for WiFi card

After some extensive searching of the web for an answer, I've reached this conclusion:
This problem can't be fixed without creating another probelm.
From what I undertand (I think), the power-save feature is disbaled in the iwl4965 & iwl3945 because it causes other problems so they decided to turn it off completely.

Lockheed

Member

Registered: 2010-03-16

Posts: 1,550

Re: Can't enable power saving for WiFi card

I came to the same conclusions, but can you confirm this function is disabled under Windows, too? Because I have a vague and unsubstantiated feeling it isn't.

newtonelectron

Member

Registered: 2012-03-29

Posts: 30

Re: Can't enable power saving for WiFi card

I came to the same conclusions, but can you confirm this function is disabled under Windows, too? Because I have a vague and unsubstantiated feeling it isn't.

Mmmm....don't have windows(7) anymore, but I'm sure it was using some sort of power saving mechanisim for the wifi card because I usually got around 30 - 40 mins more out of my battery than when running linux. Also, the fan would turn itself off occasionally when running wifi in windows. Now it's constantly humming.

Lockheed

Member

Registered: 2010-03-16

Posts: 1,550

Re: Can't enable power saving for WiFi card

Try undervolting your CPU. It helps. I also have my wificard to switch off analytically when not connected to any network while on battery.
What issues caused by powersaving under linux did you have in mind?

masteryod

Member

Registered: 2010-05-19

Posts: 433

Re: Can't enable power saving for WiFi card

Try undervolting your CPU. It helps. I also have my wificard to switch off analytically when not connected to any network while on battery.
What issues caused by powersaving under linux did you have in mind?

Is there a linux software solution for that? Cause most of the BIOSes in laptops are bare minimum and comes with no special features like voltage control/over/under/clocking.

Lockheed

Member

Registered: 2010-03-16

Posts: 1,550

Re: Can't enable power saving for WiFi card

Yes. cpupowerd (for older AMDs) and phc (for Intel).

masteryod

Member

Registered: 2010-05-19

Posts: 433

Re: Can't enable power saving for WiFi card

Yes. cpupowerd (for older AMDs) and phc (for Intel).

Wow! Thanks for that. I missed that feature so much, shame I get rid of my last notebook, but still very good news. I remember undervolting under windows k8 chip couple years ago from old machine just to squeeze couple of extra minutes on battery

Lockheed

Member

Registered: 2010-03-16

Posts: 1,550

Re: Can't enable power saving for WiFi card

There also is a script written by some guy that works more on a manual basis and replaces PHC (would probably not work on AMD) and hypothetically it could even take advantage of the built-in over clocking capabilities of C2D.

If you are interested, have a look in the thread I started at gentoo forum: http://forums.gentoo.org/viewtopic.php? … 54#6976254 .
People there are a little bit more hardware-savvy.

newtonelectron

Member

Registered: 2012-03-29

Posts: 30

Re: Can't enable power saving for WiFi card

Try undervolting your CPU. It helps. I also have my wificard to switch off analytically when not connected to any network while on battery.
What issues caused by powersaving under linux did you have in mind?

According to http://bugzilla.intellinuxwireless.org/ … gi?id=2179
it's because of a new dynamic method that was introduced into the kernel, and it breaks the two drivers (iwl4964 & iw3945). Apparently when they split iwlagn into iwl-legacy(iwl4965 & iwl3945) they were going to add the legacy power management system, but never did.