Messages in this thread | | | Date | Thu, 2 Feb 2006 11:38:33 -0800 | From | Tony Lindgren <> | Subject | Re: [PATCH] amd76x_pm: C3 powersaving for AMD K7 |
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* Erik Slagter <erik@slagter.name> [060202 01:50]: > On Thu, 2006-02-02 at 01:50 +0000, Alan Cox wrote: > > On Mer, 2006-02-01 at 20:35 -0500, Brown, Len wrote: > > > This endeavor is full of risk, and I would be extremely careful > > > about enabling features that the BIOS explicitly disabled -- > > > unless the hardware manufacturer publicly publishes > > > support for the feature, or the errata that you're working around.
Well the same code could also be used to disable C states on buggy hardware. On my Fujitsu Lifebook p2120 C states are enabled, but don't work. But we don't have currently anything in place to fix them or disable them. And enabling C states on amd76x could be a cmdline option.
> > Folks had code that supported AMD76x by banging the hardware directly. > > On some AMD76x systems it caused corruption. Nobody AFAIK ever figured > > out if it was an errata (nothing obvious in the docs/errata list) or a > > bug in the code doing the banging on the chip or some other bit of > > hardware on the mainboard that needed extra handling. > > Looks like it would be beneficial if someone, preferably with some > authority ;-), would try to get Tyan and/or AMD to reveal this > information. > > I have read the docs for the AMD768 chipset numerous times, but I least > I (okay okay, I am not the expert here ;-)) cannot find anything that > would prevent this from working correctly. > > AFAIK Tyan has been more or less cooperative with linux developers in > the past?! I'd be more than happy to ask them, but I don't think they > will take me very serious
The C states on amd76x are quite usable. The only problem I had on my Tyan s2460 was the some BIOS bug puts the machine into sleep at first when they're enabled :) This does not happen on other systems.
Tony
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