Re: machfb (sort of) working on Mach64 GX

[Michael <macallan%netbsd.org@localhost>]

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Hello,

On Apr 28, 2011, at 2:28 PM, David Riley wrote:

> The other possibility is (as mentioned) the CRT handling being  
> buggy, since the iMac had some interesting restrictions on modes.  I  
> wish my parents' old Rev B iMac was still alive and well... maybe  
> they still have it.  I'll check.

There is one way to find out if the mode setting code is the culprit  
( it probably is ).
In mach4_attach() look for this:
if (setmode)
        mach64_modeswitch(sc, sc->sc_my_mode);

and comment it out.
The idea was to use the monitor's EDID data to pick a better mode than  
OpenFirmware does ( as in, higher refresh rate if the monitor allows  
it since OF is rather restrictive in which modes it allows ), which  
may or my not work correctly on an iMac's built-in screen.

So, someone with an iMac please try the above, build a kernel with  
options MACHFB_DEBUG and send me the kernel output ( it should contain  
a dump of the monitor's EDID block ). With that I should be able to  
tell wether the logic that picks a video mode is faulty ( it probably  
is, since the iMac's CRTs require a fixed horizontal frequency which  
is rather unusual ).

have fun
Michael

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