[PATCH] i810: Add workaround for bad BIOS mode on Fujitsu laptops

[Tony Lindgren]

* Eric Anholt <eric at anholt.net> [070129 09:21]:
> On Sun, 2007-01-28 at 23:32 -0800, Tony Lindgren wrote:
> > * Keith Packard <keithp at keithp.com> [070128 23:22]:
> > > On Sun, 2007-01-28 at 22:48 -0800, Tony Lindgren wrote:
> > > > Hi all,
> > > > 
> > > > Just hacking a bit to get the i810 modesetting driver to work on my
> > > > laptop :) Here are few patches.
> > > 
> > > We've started adding a list of 'quirks' to the EDID parsing stuff;
> > > perhaps we need a similar list of quirks for the BIOS data.
> > 
> > OK. Originally when trying to fix this I was thinking that the BIOS
> > mode should be verified against all the probed modes, and if the BIOS
> > mode does not match any VESA modes, then ignore the BIOS mode. But
> > then I noticed that the probed modes use BIOS mode for some
> > checks..
> > 
> > Maybe there should be some option to ignore BIOS mode? And then have
> > some quirks for known bad BIOS modes.
> >  
> > > It looks like you're just whacking the hsync values; can you describe a
> > > bit more verbosely what happens when you use the BIOS mode? Obviously,
> > > if we can fix up the driver so that the BIOS mode works, that would be
> > > nicer than discovering that the BIOS data is actually broken.
> > 
> > Yeah, the LVDS is streched out estimated 2x horizontally, vertical is
> > OK without the patch. Are you suggesting that the bug would be in the
> > BIOS mode parsing?
> >  
> > > Can the BIOS set the mode correctly?
> > 
> > I don't think so unless there's a bug in parsing the BIOS mode.
> > I guess I could try to dump the BIOS, or let me know what data
> > you need.
> 
> Yeah, the BIOS parsing code is based on how Intel's BIOS tables are
> formatted, but your laptop manufacturer may have chosen to mess with
> things.  We've already got one workaround for how a vendor played with
> the formatting, and could certainly do more if that's appropriate.  The
> other possibility is if your laptop happens to expose DDC for the panel,
> we could fix the driver to trust DDC EDID data over what we pull out of
> the BIOS.  However, if you don't have DDC, I'd be fine with adding your
> patch.

No DDC here for the panel unless there's something else that needs to be
enabled that I'm not aware of. I'll try to play with the BIOS parsing
when I have a chance.

Regards,

Tony