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From: Patrick Mochel <>
To: Benjamin Herrenschmidt <>
Cc: linux-kernel mailing list <>
Subject: Re: Subtle semantic issue with sleep callbacks in drivers
Date: Wed, 16 Apr 2003 11:31:26 -0700 (PDT)	[thread overview]
Message-ID: <Pine.LNX.4.44.0304161124400.912-100000@cherise> (raw)
In-Reply-To: <>

> So basically, the "state" parameter should encore not only what state
> we want to go to, but rather, what will happen to the slot:
> - Nothing (it's entirely up to the driver to do it's own power
> management, that happens for some devices inside Apple ASIC), though in
> this case at least, those driver have control over the chip power, reset
> lines, etc...
> - Slot will be unclocked (it's up to the driver, it the chip supports
> static mode, to go to D2 or D3 if the driver can deal with it, though
> the system will do nothing to help the driver)
> - Slot will be powered off. This case should be broken up (via an
> additional flag passed to the driver ?) into 1) the system _will_
> re-POST the card before resume (BIOS/ACPI support, swsusp) or the
> system will NOT re-POST the card, the driver shall fail the sleep
> request if it can't do it by itself.
>  - Embedded people may have even more weird cases ?

This is not necessarily a slot-by-slot question, but whether the entire 
PCI/AGP buses will lose power during the sleep state, right? 

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. 

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.

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 


  parent reply	other threads:[~2003-04-16 18:20 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-04-14 10:00 Subtle semantic issue with sleep callbacks in drivers Benjamin Herrenschmidt
2003-04-14 10:11 ` Benjamin Herrenschmidt
2003-04-16 18:31 ` Patrick Mochel [this message]
2003-04-16 19:29   ` Benjamin Herrenschmidt
2003-04-23 15:32 ` Pavel Machek
2003-04-14 17:09 Grover, Andrew
2003-04-14 17:40 ` Benjamin Herrenschmidt
2003-04-23 15:29 ` Pavel Machek
2003-04-14 19:07 Grover, Andrew
2003-04-14 19:18 ` Benjamin Herrenschmidt
2003-04-14 19:56 ` Alan Cox
2003-04-23 15:34 ` Pavel Machek
2003-04-14 21:09 Grover, Andrew
2003-04-16 18:39 ` Patrick Mochel
2003-04-16 19:36   ` Benjamin Herrenschmidt
2003-04-17 13:35   ` Alan Cox
2003-04-17 14:48     ` Jeff Garzik
2003-04-17 15:09       ` John Bradford
2003-04-17 15:09         ` Jeff Garzik
2003-04-17 15:47           ` John Bradford
2003-04-17 15:56             ` Jeff Garzik
2003-04-17 16:24               ` Alan Cox
2003-04-18  7:37             ` Greg KH
2003-04-18  7:51               ` John Bradford
2003-04-18  9:10               ` Russell King
2003-04-18 11:18                 ` Alan Cox
2003-04-18 11:30               ` Alan Cox
2003-04-29  8:28         ` Pavel Machek
2003-04-17 14:59     ` John Bradford
2003-04-17 15:04       ` Alan Cox

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