Twister savagefb doesn't sync

[Vassilis Virvilis <vasvir@iit.demokritos.gr>]

Hi,

I am a newcomer to the list so please forgive any unforgivable mistake I may do.

The problem at hand is savagefb. The specific model is 0x5333:0x8d01 (twisterP).
I am using a recent enough kernel and I am trying to use fb through SDL.

I believe SDL is not the problem because one of the monitors I tried it is
an EIZO FlexScan 520 that has the extremely nice feature to report the freequency
of the signals the graphics adaptor emits.

See the table:
         640x480       800x600        1024x768
bpp 8   23.1/28.7     26.8/33.2       48.3/59.9 (works)
bpp 16  18.6/23.1     26.8/33.2       33.2/41.2
bpp 32  18.6/23.1     29.7/36.8       33.2/41.2

That means that 640x480x8 emits Horizontal sync at 23.1KHz / VF 28.Hz
which is out of the sync range of any monitor. So the savage clocks are
not programmed correctly (sorry for awkard use of terminology but I am
hardly a graphics expert).

As a workaround for my EIZO I tried (succesfully)

#This syncronize at 100Hz vertical refresh rate
#fbset -xres 640 -yres 480 -depth 16 -t 9260 48 16 33 10 96 2
#This syncronize at 60Hz vertical refresh rate (fbset -i repors 160Hz)
fbset -xres 640 -yres 480 -depth 16 -t 15385 48 16 33 10 96 2

This is not working for my other monitor a TFT Medion (1280x1024). So
I guess that makes it an EDID dependent bug.

So I tried to look the X source code. Looks like it is from the same
codebase more or less with the in kernel savage driver. However the
X driver supports the Option UseBios for mode switching. The default
setting is yes. I tried to disable it and bingo. X exhibits similar
behaviour to the FB driver. It programs the clocks like above. (more or less
I didn't try all the combinations).

So AFAIU neither kernel nor X knows how to program the specific savage card.
I would like it to debug it further but I don't know from where to start.
The code is nicely written but incomprehensible if you don't have the
manual in order to see what all these registers do.

I know howto patch/compile/test and I am willing to help with this if
there is somebody which can guide me a little bit.

          .bill


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