Re: is L1 really disabled in iwlwifi

[Stanislaw Gruszka <sgruszka@redhat.com>]

On Mon, Mar 04, 2013 at 10:41:14AM +0200, Emmanuel Grumbach wrote:
> In 1a7123cdd9f49cf1c908fb2c16d26f279c88d8c9, John Linville disabled
> ASPM for iwlwifi:
> 
> 	/* W/A - seems to solve weird behavior. We need to remove this if we
> 	 * don't want to stay in L1 all the time. This wastes a lot of power */
> 	pci_disable_link_state(pdev, PCIE_LINK_STATE_L0S | PCIE_LINK_STATE_L1 |
> 			       PCIE_LINK_STATE_CLKPM);
> 
> Now, I took a laptop with 3.7.9 (that supports L1) and measured power.
> I would expect to see that as long as the driver isn't loaded, the
> power consumption is low (L1 enabled), and when I load the driver, the
> power consumption rises because L1 gets disabled.
> But this is not what I see. I see more the less the same numbers
> before and after driver load.
> I don't remember exactly the numbers, but I do remember they were low
> (around 1mA or so) - but I really need to check.
> I also removed the code above, and it didn't change anything.
> Can it be that this code doesn't have any effect?

Depend on BIOS settings ASPM can be enabled or disabled on the whole
system. I think kernel can change settings globally as well.
Reloading driver can not be enough to check that, try to reboot the
system with iwlwifi module blacklisted and check lspci -vvv to see
LnkCtl ASPM settings.

Additionally despite above code, iwlwifi try to enable L0S in
iwl_pcie_apm_config(), what is basically wrong. 

Stanislaw