RE: atyfb: brokenness on PowerMac 5500 and Beige G3

Okay, I made some very important progress:

I hard-coded the correct values into dsp_config and dsp_on_off. Presto - no
more disruption.
But the code does seem to boot when using quik. Which means that when OF
initializes the card, it sets some values that are not being touched later
on, or at least used to generate the (bogus) dsp_config and dsp_on_off.
Since the BIOS probe code entered, maybe the driver was cleaned of forced
programming of registers, which macs depended on for correct operation.

Gil Bahat,
System Administrator.

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Gil
Bahat
Sent: Saturday, November 05, 2005 7:15 PM
To: [email protected]
Subject: RE: [Linux-fbdev-users] atyfb: brokenness on PowerMac 5500 and
Beige G3

Hello,

I have now decoded and mapped the register differences as they appeared in
http://patchwork.ozlabs.org/linuxppc/patch?id=1268. However, I have went
through the code path and cannot explain most of the reasons for the
changes, nor can I estimate their effect. That's where the list might come
handy :)

So, after applying the patch:

BUS_CNTL changes from 7b23a040 to 7b23a050. this is due to the code section
that enables auxillary aperture to enable access to 8mb memory cards.

CRTC_GEN_CNTL changes from 03000200 to 0b000200. I have noticed the code in
mach64_ct.c has removed a particular bit masking when assigning GEN_CNTL,
but I have no idea why.

DSP_CONFIG also changes. It becomes 004805FA instead of 004808e2. no idea
why - the code that generates it looks the same to me.

DSP_ON_OFF also changes. It becomes 00B4043B instead of 009C0666. ditto for
the reasoning.

PLL is also different in its first 24 bytes:
ADD52414 instead of ADD52144
A80382D1 instead of E80382D1
8E829601 instead of 8E9E9814
I don't know how to decode this yet.

Can anyone have a look at mach64_ct.c and maybe notice what I haven't
noticed regarding the DSP programming?

Thanks,

Gil Bahat,
System Administrator.



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