Re: [RFC] Reliable video POSTing on resume (was: Re: Samsung P35, S3, black screen (radeon))

Pavel Machek
2005-02-07T20:59:58Z

Hi!

> > > > We already try to do that, but it hangs on 70% of machines. See
> > > > Documentation/power/video.txt.
> > >
> > > We know that all of these ROMs are run at power on so they have to
> > > work. This implies that there must be something wrong with the
> > > environment the ROM are being run in. Video ROMs make calls into the
> > > INT vectors of the system BIOS. If these haven't been set up yet
> > > running the VBIOS is sure to hang. Has someone with ROM source and
> > > the appropriate debugging tools tried to debug one of these hangs?
> > > Alternatively code could be added to wakeup.S to try and set these up
> > > or dump the ones that are there and see if they are sane.
> >
> > Rumors say that notebooks no longer have video bios at C000h:0; rumors
> > say that video BIOS on notebooks is simply integrated into main system
> > BIOS. I personaly do not know if rumors are true, but PCs are ugly
> > machines....
>
> The state of current hardware has already been mentioned but let
> me clarify. This is not a laptop problem anytime you have onboard
> video you are unlikely to have a separate video ROM. This includes
> many recent server boards as well as laptops. When the board boots
> up there will be a video option ROM shadowed into the usually location
> at C000h:0 but what becomes of it afterwards is a good question.
>
> For server boards most commonly this seems to be a flavor of the ATI
> Rage XL chip. It is a low end part that I doubt getting documentation
> for will be very hard. And according to
> Documentation/power/video.txt this is one of the cases that actually
> works.

I do not see Rage XL mentioned in video.txt; can you give me details
and/or suggest a patch?

> What is happening in those POST routines of a video card is typically
> the code to initialize the memory controller on the video card. Plus
> a little bit of code to set the video mode. If I read the
> documentation correctly in a S3 power state only the RAM is preserved.
> So it does look like the video post is needed.

On some machines, video state is preserved over S3... Some BIOSes are
good enough to POST video for you...
Pavel
--
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