it is a very complicated issue. Different system have different limitation. it is not a one size fits all. So we let the BIOS of each system with the different chipset control this, and we work with that team to make sure the correct settings work together for both RC and endpoint. It should not be controlled by the endpoint as endpoint can get plug into many different systems and endpoint will not know the limitations of each system/chipset in the system. I highly recommend you all not to touch the aspm settings from the endpoint, point of view and let the system bios do what it has been programmed to do. David -----Original Message----- From: Luis R. Rodriguez [mailto:mcgrof@xxxxxxxxx] Sent: Friday, April 16, 2010 12:54 PM To: linux-wireless Cc: linux-kernel@xxxxxxxxxxxxxxx; yanmin.zhang@xxxxxxxxx; shaohua.li@xxxxxxxxx; Sameer Nanda; Jonathan May; David Quan Subject: Power consumption on 802.11 / ASPM / device measurements We've been accumulating a few power consumption related documents on the wireless wiki for a while now. One which I saw was missing was for actual power consumption and review of new PCI-E features which should be taken into consideration when debugging power consumption or reviewing it. ASPM is something that I can say I found little to no documentation for when looking into it so I've done a brain dump of what I recall from it, the code review of it, and some e-mail exchanges I've had with Jonathan May @ Atheros. I've stashed together all the power consumption docs at: http://wireless.kernel.org/en/users/Documentation/Power-consumption You'll see there some ASPM docs now and some ath9k specific power consumption metrics/ASPM details. Please review and enhance as you see fit. Yanmin, Shaohua, I see CONFIG_PCIEASPM still marked as experimental, I'm curious if this is still really that experimental and if there are plans for it go out of experimental. Also I am little puzzled with some of the aspm.c code, I see we fill the pci device struct with capability stuff via pcie_aspm_cap_init() but I also see ASPM capability stuff exposed on kernels without CONFIG_PCIEASPM (albeit I see it always disabled on my system at home), so are we filling the capability elsewhere? I think there are some boxes without this kernel config enabled and where ASPM capability info is exposed and does show up as enabled, could be wrong. Also curious -- how often are BIOSes buggy enough for ASPM to get disabled by mistake on the modern devices? And for systems that have no Bios (*cough* ChromeOS) how is this handled? Luis -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
