On Tue, Oct 22, 2002 at 10:37:07PM -0400, David Dawes wrote:
> On Tue, Oct 22, 2002 at 09:52:26AM +0200, Ducrot Bruno wrote:
> >On Mon, Oct 21, 2002 at 05:14:28PM -0400, David Dawes wrote:
> >> On Fri, Oct 18, 2002 at 08:38:22AM +0100, Philip Blacker wrote:
> >> >>> I'm wondering if it's feasible for the kernel to route ACPI power 
> >
> >
> >[...]
> >
> >> Does it make a difference if you switch to a text VT before initiating
> >> a suspend?  That's how XFree86 handles APM suspend/resume.  With a
> >> correctly implemented VTEnter(), the driver should then reinitalise the
> >> hardware correctly when switching back to the X server after resuming.
> >> Some drivers don't to enough hw state initialisation in their VTEnter()
> >> function to handle returning from suspend.
> >> 
> >> All of this assumes that the BIOS (and OS?) put the video hardware back
> >> into a sane text console state -- ideally the same state as after a
> >> normal system boot.  If that doesn't happen, then there are likely to
> >> be problems.
> >
> >No difference.  It is already a common trick for swsusp people.
> >I don't see anything in the code that could explain why a perticular
> >xaa extension is no more functionnal for this card.
> >For me, VTEnter() from the nv driver seems to be correct.
> >
> >[...]
> >
> >> >Another way to solve the problem is to start another Xserver on another 
> >> >display then kill it.  This probably does the reset that should come 
> >> >though APM.
> 
> If VTEnter() is doing everything needed, I'm wondering why starting another
> X server then killing it solves the problem.

Me too.  And the bad news is that I really do not understand what happens
here.

> >> If swsusp can use some equivalent of apmd (or acpid), it should be
> >> possible to have that daemon force a VT switch on suspend, and switch
> >> back on resume (using chvt(1) as I suggested above).
> >> 
> >> >I think adding ACPI support to XFree86 is the way to go rather than a 
> >> >user space deamon.  Kernel 2.4.20 is going to have a (almost) fully 
> >> >working ACPI implementation, the swsusp patch will still be needed for 
> >> >S4(suspend to disk), S1 (suspend to RAM) will work on some machines.
> >> 
> >> What's the current state of acpid?
> >
> >Nothing is done from swsusp to send power management notifications to
> >user space before suspension.  The same apply for ACPI.
> 
> What's the use of acpid if it doesn't get any notifications before
> suspension?  Is everything that needs to be done expected to be handled
> in the kernel?

Yes.  All processes are 'frozen', then a suspend event to all devices
is send.  If swsusp want to notify the suspension to user processes, it
will require a major redisign at this stage.  Same apply also for ACPI
(under Linux, I do not speak for *BSD) because it call swsusp (for 2.5
kernels only) to implement S4.

-- 
Ducrot Bruno
http://www.poupinou.org        Page profaissionelle
http://toto.tu-me-saoules.com  Haume page
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