[Nouveau] [PATCH] Add PFIFO and PGRAPH pausing methods

[Martin Peres]

Hi,

I'm still working on getting the reclocking work done right. There are 
several parts I identify:
- Pausing PFIFO (with its caches), pause PGRAPH and wait for idle
- Stop some PLL (I guess it is more, physically disconnect them from the 
engines) using the 0xc040 register.
- reclock memory
- reclock the other engines
- Make sure the display doesn't blow up
Depending on the cards, I have completed all of the steps or none.

Anyway, pausing PFIFO and PGRAPH works well on all the card I tested and 
so, I would like it to be pushed.
I have a new theory upon the PLL_SUPERVISOR(0xc040) that I want to test. 
When I'm done with this, I'll put together a patch for it and continue 
on the other steps.

Please provide me with some feedback on the patch or push it if nothing 
bothers you.

Martin

PS: I'm quite busy at the moment, I'll write an in-depth mail when I've 
verified my theories and got proper support on other cards than the nv86 
ones.