SIS 648FX AGP fixed - but clarification needed

[Heilmann, Oliver]

I have an SIS 648FX in a notebook computer with an ATI Radeon9600 (M10)
AGP card. AGP did not work so I had a look and found that ATTBASE had
moved to caps + 0x18, AGPCTRL needed to be set and that there was a
weird delay after the bridge has been enabled(see below). Things work
now.

I would like to put my fix into a proper patch but am still unclear on
the following points:

1. According to sis_agp_device_ids the 648 chipset is supported. Does
this mean that the "plain" 648 is actually supported and my "FX"
iteration is so fundamentally different (even thought is has the same
device id).

2. Once the agpEnable bit is set in the bridge's cmd register the config
space of the master is completely screwed up for a while. Trying to
configure/enable the master during that period mostly crashes the
system. Waiting does the trick. (Annoyingly, simply waiting for the
master to become readable again is not good enough, one still needs to
wait longer for things to become stable). None of the other chipsets
seem to need this. Can anybody explain? Perhaps I missed something? If
there is no other way and I do have to stick with the delay, then I
suppose it would not be a good idea to polute the generic agp_enable
with it?!

Oliver


-- 
Oliver Heilmann <oliver.heilmann@xxxxxxxx>


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