Debugging the Radeon 200M command processor (CP)

[Phillip E. <phi...@gm...>]

Hi All,

   I've been hacking away at the 200M driver without much success, and would
like to hear if other people with more radeon experience can help me. I have
things setup to use 128M of the sideport memory (and nothing else).  I've
been both userspace (libsegfault) and kernelspace (kmmio) register tracing
to capture all of the accesses that the fglrx driver/library does to the
card.

...
There are many problems, but I want to start at the beginning.
First, the stipple pattern doesn't appear on the screen when X starts up.
As you may know, for radeon, this is done with DRI using indirect buffers to
draw the stipple.

Oddly, the pattern never shows up on my screen AND the indirect pointer
(CP_IB_BASE) register is set to the value "000000000", so it doesn't look
like the CP is even executing the command.  (When the firglx runs for a
while, this register is set to something sensible.. (0x58710000) )

I tried to avoid the whole "indirect buffer" issue, so on every call to the
indirect DRM ioctl, I issue the commands directly to the ring buffer and
return. (I just copied the values which X wrote to the indirect buffer.)
However, things still don't work correctly.

CP
---
1) Could the CP be drawing this stuff, but putting it offscreen somewhere?

2) Could the command stream be wrong?

3) In the fgrlx 8.32.5 driver, the cp mode (RADEON_CP_CSQ_CNTL) is set to
(0x80000000), which doesn't correspond to ANY of the modes listed in the
radeon_regs.h file.  Does anyone have any idea what that value means?

4) Is there a simple command that I can issue to the CP to clear the screen
JUST to see if it is issuing any commands from the ring buffer at all?

Ring Buffer
----------------
I'm beginning to suspect that the CP is just executing random commands, and
I happen to get lucky that things start up at all.

1) The fglrx driver never sets the (RADEON_CP_RB_RPTR_ADDR) register.  If I
read the register back when fglrx is running, it is set to "0".

What does that register indicate?

GART

1) The fglrx driver also never sets ANY of the the pciexpress registers. (or
any of the  RADEON_AIC_*) Also, if I try to read the PCI Express registers
when fglrx is running, the values are all set to zero.

(Oddly, the PCIE index register: 0x00000030 is written to, but it is never
follwed by reads/write to 0x00000034... However, the radeon_drv.h file also
lists 0x00000030 as the bus control register, so maybe it is using it as
that. )

Is it possible that this card does use a GART? (Or is that crazy talk..)

Thanks,
--Phil