On Tue, Jun 22, 2010 at 10:40:15AM -0700, Luis R. Rodriguez wrote: > On Tue, Jun 22, 2010 at 10:25 AM, Matthew Garrett <mjg59@xxxxxxxxxxxxx> wrote: > > Right, which we have to deal with by having drivers disable ASPM on > > broken devices. > > Agreed, but then the assumption would be drivers are ASPM bug free > which is expect to be false with Video and 802.11 given that only a > handful of vendors do actually get involved with their drivers > upstream. Safe thing of course is to just disable it, of course, but > if you are going to use pcie_aspm=force good luck! People who use "force" deserve whatever they get, but "powersave" really ought to work. Fedora's defaulted to that for a while now - we've hit issues with aacraid, but that's pretty much it in terms of cases where the heuristics don't work. Maxim's problems wouldn't be triggered because CONFIG_PCIE_ASPM disables it on pre-1.1 devices regardless of the BIOS setup. > > Having looked into this, Windows will enable ASPM on external > > controllers unless there's some reason for it not to - where that may be > > either the appropriate bit in the FADT being set, the device not being > > PCIe 1.1 or later, there being no _OSC method on the appropriate root > > bridge or the _OSC method not giving it full control over PCIe, the > > driver disabling ASPM or the device not advertising it in the first > > place. > > I was unaware of all this root complex sanity checks on Windows, > thanks for sharing. With the patch I've just sent, they should also all be used for Linux as well. > I suspect these tweaks will go away as the industry produces cards > with both L1 and L0s enabled all the time (devices being produced > today), but for devices caught in that middle of time between whether > or not L0s would be *required* (last 2 years) I suspect we'll run > into these issues. If the same problems would appear under Windows then it's not a problem that I'm hugely concerned about as yet - we'll wait a bit longer and then change the ASPM defaults to be more aggressive under Linux, and if it turns out to be a significant problem in the real world we'll have to reconsider it. But I don't think we should be depending on userspace bashing hardware registers in order to be able to enable power management. -- Matthew Garrett | mjg59@xxxxxxxxxxxxx -- 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
