(Alex, this is just an FYI in case you're interested :)
Okay, I think I'm there.
There appears to be a fairly serious bug in the function
gfx_is_display_mode_supported() in
xc/programs/Xserver/hw/xfree86/drivers/nsc/gfx/disp_gu1.c from
yesterday's CVS.
Not being familiar with XFree86 internals, I'm not sure if this is
/actually/ a bug in the function itself, or in the overlying code, or in
the display modes table in
xc/programs/Xserver/hw/xfree86/drivers/nsc/gfx/gfx_disp.c. I just fixed
the symptoms.
The problem is that the aforementioned table contains actual pixel
scanline heights (e.g. 320 x 240 has a vertical size of 240), whereas
the input scanline height supplied to the function will be 480 (IOW beam
scanlines, not pixel scanlines). This means that
gfx_is_display_mode_supported will never find any mode that's supposed
to be scandoubled; hence, these modes are currently totally broken on
Geode.
I modified the above function to check if the current mode's flags
indicate doublescanning, and if so it generates a bogus doubled
scanheight for comparison purposes.
The following three patches fix this bug and alter a couple of minima,
thereby enabling lo-res video modes on the Geode platform:
Note! Xv support is still at least partly broken in these modes, I
believe.
--- Begin patch for disp_gu1.c
130a131,135
> /*
> * Bugfix to gfx_is_mode_supported to fix problems with doublescan
modes
> * Lewin A.R.W. Edwards <[EMAIL PROTECTED]>
> */
>
839d843
<
840a845,850
> int tmp_yres;
>
> tmp_yres = yres;
> if (DisplayParams[mode].flags & GFX_MODE_LINE_DOUBLE)
> tmp_yres = tmp_yres / 2;
>
842,843c852,853
< (DisplayParams[mode].vactive == (unsigned short)yres) &&
< (DisplayParams[mode].flags & hz_flag) &&
---
> (DisplayParams[mode].vactive == (unsigned short)tmp_yres) &&
> (DisplayParams[mode].flags & hz_flag) &&
850a861
>
878a890
>
--- Begin patch for nsc_gx1_driver.c
150a151,155
> /*
> * Minor patches to allow support of low-res video modes
> * Lewin A.R.W. Edwards <[EMAIL PROTECTED]>
> */
>
475c480
< { NULL, 25175, 135000, 0, FALSE, TRUE, 1, 1, 0 };
---
> { NULL, 10000, 135000, 0, FALSE, TRUE, 1, 1, 0 };
937c942
< minHeight = 480;
---
> minHeight = 200;
1850c1855,1856
< if (MemIndex == -1) /* no match */
---
>
> if (MemIndex == -1) /* no match */
2363a2370
>
--- Begin patch for nsc_gx2_driver.c
145a146,150
> /*
> * Minor patches to allow support of low-res video modes
> * Lewin A.R.W. Edwards <[EMAIL PROTECTED]>
> */
>
474c479
< { NULL, 25175, 229500, 0, FALSE, TRUE, 1, 1, 0 };
---
> { NULL, 10000, 229500, 0, FALSE, TRUE, 1, 1, 0 };
911c916
< minHeight = 480;
---
> minHeight = 200;
--
-- Lewin A.R.W. Edwards
Work: http://www.digi-frame.com/
Personal: http://www.larwe.com/
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