[Intel-gfx] PANEL_FITTING atom

Lovelace Luquette luquette at bu.edu
Tue Aug 5 04:11:57 CEST 2008

On Mon, 4 Aug 2008, Jesse Barnes wrote:

> 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.

Alright, I'll see what it does on my platform.

If the PFIT_* registers don't end up working, is there any other way I 
could get around the full-x/y scaling method?

Joe Luquette

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