RE: Subtle semantic issue with sleep callbacks in drivers

[Grover, Andrew]

> From: Benjamin Herrenschmidt [mailto:[e-mail]] 
> On Mon, 2003-04-14 at 19:09, Grover, Andrew wrote:
> > Ben obviously PPC is ahead of the pack on this stuff 
> (congrats) but I 
> > did just want to put forward the idea that when we're all done with 
> > this stuff on all archs, we will hopefully not be regularly 
> re-POSTing 
> > the video bios.
> 
> But how ? let's make clear what we call POST first ...
> 
> If the card is powered off, it must be POSTed to be brought 
> back to life. Either we do it by running the BIOS code 
> (probably what you are talking about and should be 
> deprecated), or the driver "knows" how to restore the chip 
> from power off. I don't know if APM/ACPI provides other ways, 
> I suspect the APM BIOS will re-POST the card by itself or 
> else, things wouldn't work today. I don't know about ACPI.
> 
> What I mean here is that none of our drivers know how to bring 
> back a chip as complicated as a radeon or a nvidia up from 
> power off, this requires intimate knowledge of the chip 
> internals, the way it's wired on a given board, etc...

All I am saying is that on Windows, the driver gets no help from the
BIOS, APM, or ACPI, but yet it restores the video to full working
condition. I understand that this sounds complicated, but since there is
an implementation that already does this then I think we have to assume
it's possible. :) Perhaps we should start with older, simpler gfx hw, or
maybe POST the bios, but only as an interim solution until gfx drivers
get better in this area.

Regards -- Andy