Re: +pm-gxfb-add-hook-to-pm-console-layer-that-allows-disabling-of-suspend-vt-switch.patch added to -mm tree

From: Pavel Machek
Date: Thu Mar 13 2008 - 06:12:49 EST



> > > (Note: I'm not convinced that console_sem is the best way to protect this, but
> > > we should probably have some form of locking..)
> >
> > I guess this is okay for now, but we probably want to make it more
> > elaborate in future.
> >
> > Console switch is there to make sure kernel (not X) owns the graphical
> > hardware.
> >
> > That is unneccessary for gxfb since X never owns graphics hardware,
> > good. (I do not see why it is optional, then. Do you really want to
> > see tty1?)
>
> Its the dream for the lxfb and gxfb to own the graphics hardware
> completely (at least, thats what Jim Gettys keeps pounding in to my
> brain), but we're not quite there yet. What we have here are
> framebuffer drivers that are intelligent enough to save and restore the
> state of the graphics engine, which is still a lot better then most other
> drivers.

Ok.

> > Now, question is what happens with two graphics cards, one of them
> > driven by X. Fortunately that is uncommon.
>
> We would be screwed. But since the Geode has built in graphics logic,
> it doesn't make much sense to use an external card, so we'll mostly
> avoid this problem. But even if it happens, we'll have the VT switch
> available in a pinch.
>
> > Also, it would be nice to make the logic the other way around. Move vt
> > switching to the drivers that need it because X can be expected to own
> > the hardware.
>
> Conservation of energy. Its easier to make 3 or 4 drivers opt out of

Nice euphemism. You did quick hack instead of proper solution, and
someone will have to clean it up sooner or later...
Pavel

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