RE: Subtle semantic issue with sleep callbacks in drivers

Grover, Andrew (andrew.grover@intel.com)
Mon, 14 Apr 2003 12:07:18 -0700


> From: Benjamin Herrenschmidt [mailto:benh@kernel.crashing.org]
> 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
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