[Intel-gfx] PANEL_FITTING atom

Jesse Barnes jbarnes at virtuousgeek.org
Mon Aug 4 22:56:25 CEST 2008

On Monday, August 04, 2008 6:40 am Lovelace Luquette wrote:
> Hi,
> I'm using an Intel i852GM chipset and have a 16:10 aspect ratio LCD.
> I'd like to be able to configure the PANEL_FITTING atom introduced in 2.3.
> However, looking through the code, I see that the PANEL_FITTING atom is
> disabled for all of the i8xx chips.  For these chips all I can do is
> accept the default setting of PANEL_FITTING = full.
> The code for letterboxing/pillar-boxing seems to be really simple.  (Even
> for i8xx chips, it seems like all we have to do is set PFIT_CONTROL to the
> appropriate mode, then find the drawing offset and store it in
> Is the reason we can't implement the PANEL_FITTING atom for i8xx because
> the i8xx chips don't have the PFIT_CONTROL and PFIT_PGM_RATIOS registers?
> (As a side note: this doesn't seem to be the case since all of the PFIT_*
> registers are declared in i810_regs.h.  As another side note, when I dump
> the chip's registers I see PFIT_CONTROL and PFIT_PGM_RATIOS in the dump.)

Right, and I think we saw PFIT programming cause trouble on at least a few 8xx 
platforms (even though they appeared to have PFIT regs).

> I found the register documentation at http://intellinuxgraphics.org for
> 965+ chips; is there a similar place to find register documentation for
> older chips or has intel not released that data?

Our internal 8xx documentation doesn't list the PFIT regs, though on some 
chips they may work anyway.  If they work fine for you after removing the 8xx 
checks in the PFIT code, we could add a whitelist for your platform to make 
things work automatically.


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