On Mon, Mar 04, 2013 at 10:41:14AM +0200, Emmanuel Grumbach wrote: > Hi, > > 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? > > And as you can see, I am not an expert at this... Neither am I...that commit was a couple of years ago, and the code seems to have moved around a bit since then. FWIW, the "W/A - seems to solve..." comment isn't even mine. I don't even know what "W/A" means...? Anyway, ISTRC that change being suggested by Wey-Yi in response to some device disconnects (i.e. from the PCI-E bus). I have no idea how much power it should cost or if it is really even necessary. John -- John W. Linville Someday the world will need a hero, and you linville@xxxxxxxxxxxxx might be all we have. Be ready. -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
