Re: [PATCH] Framebuffer: client notification mecanism & PM

Re: [PATCH] Framebuffer: client notification mecanism & PM

[James Simmons]

> > matroxfb tried to use a 'dead' for handling hot removal, but your code
> > looks definitely saner
> 
> My code wasn't really intended to deal with hot-removal, more with
> "what happens if printk occurs during the Power Management suspend
> sequence", but I tried to keep the notification mecanism simple
> enough so it could be used for that as well. Also, indeed, the fbcon
> changes should deal with hot-removal in some way (though you surely
> also want to "deatch" from the fbdev's in this case).
> 
> Among other things that could be used for is live monitor insertion/
> removal detection (some HW are able to do that), "pivot" monitor
> kind of things, etc... typically via the mode_changed hook.

I knew it was a matter of time before "client" management would happen. 
Is this a 2.6.X thing tho or shoudl we wait for the next developement 
cycle. I don't mind working on experimental stuff.




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Re: [PATCH] Framebuffer: client notification mecanism & PM

[Benjamin Herrenschmidt]

On Tue, 2003-07-29 at 12:55, James Simmons wrote:
> > > matroxfb tried to use a 'dead' for handling hot removal, but your code
> > > looks definitely saner
> > 
> > My code wasn't really intended to deal with hot-removal, more with
> > "what happens if printk occurs during the Power Management suspend
> > sequence", but I tried to keep the notification mecanism simple
> > enough so it could be used for that as well. Also, indeed, the fbcon
> > changes should deal with hot-removal in some way (though you surely
> > also want to "deatch" from the fbdev's in this case).
> > 
> > Among other things that could be used for is live monitor insertion/
> > removal detection (some HW are able to do that), "pivot" monitor
> > kind of things, etc... typically via the mode_changed hook.
> 
> I knew it was a matter of time before "client" management would happen. 
> Is this a 2.6.X thing tho or shoudl we wait for the next developement 
> cycle. I don't mind working on experimental stuff.

We need that now for proper power management.

Ben.

Re: [PATCH] Framebuffer: client notification mecanism & PM

[James Simmons]

> > I knew it was a matter of time before "client" management would happen. 
> > Is this a 2.6.X thing tho or shoudl we wait for the next developement 
> > cycle. I don't mind working on experimental stuff.
> 
> We need that now for proper power management.

Okay. 




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Re: [PATCH] Framebuffer: client notification mecanism & PM

[Benjamin Herrenschmidt]

> > I knew it was a matter of time before "client" management would happen. 
> > Is this a 2.6.X thing tho or shoudl we wait for the next developement 
> > cycle. I don't mind working on experimental stuff.

Note, BTW, there's also a locking issue. Typically, we must make sure
the fbcon (which may be running another CPU) have finished doing whatever
it was doing before returning, and we don't get any mode change or 
whatever ioctl initiated thing at that moment (or be in the middle of
doing it).

Right now, my code assumes any operation on the fbdev is protected by
the console sem. However, looking at the console & fbmem code, that is
not always true. Typically, userland ioctls in fbmem aren't, and vt.c
may call into consoles in some cases without holding it neither.

That should probably be fixed, though I haven't had time to work on
it yet.

Ben.



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