Messages in this thread | | | Subject | Re: Subtle semantic issue with sleep callbacks in drivers | From | Benjamin Herrenschmidt <> | Date | 16 Apr 2003 21:29:52 +0200 |
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On Wed, 2003-04-16 at 20:31, Patrick Mochel wrote:
> This is not necessarily a slot-by-slot question, but whether the entire > PCI/AGP buses will lose power during the sleep state, right?
This is really per-slot. Especially on embedded or laptops, you really don't know how each slot is wired regarding the power planes.
> There are a couple of things to note. > > This is only an issue when doing suspend-to-RAM. Suspend-to-disk, and > power-on suspend will definitely lose power and definitely not lose any > power, respectively. So, you need a mechanism to determine what state the > system is entering.
Yes.
> Next, once you determine that we're entering suspend-to-RAM, you need to > know if the buses will lose power. In order to have a generic suspend > sequence, there must be a set of platform-specific methods to do all the > fun platform things that must be done. In that object, we can easily add a > flag that specifies whether or not the platform will lose power. This flag > can be initialized based on platform knowledge on startup.
It's individual to each device though. And we must also have a flag the platform can use to indicate it can/will re-POST the card (by re-running the BIOS or whatever firmware)...
> In short, there should be no problems. Hopefully, I should have something > within the week to review/test. (Yeah yeah, talk is cheap, but I'm getting > there).
Good :) I'm getting there too for the pmac implementation finally...
Ben.
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