[Bug 69723] Computer freezes with kernel 3.11.0 / 3.12-rc1 (with bug 68235's patches applied) when dpm=1 on r600g (Cayman)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=69723

--- Comment #13 from Alexandre Demers <alexandre.f.demers at gmail.com> ---
(In reply to comment #12)
> (In reply to comment #11)
> > (In reply to comment #10)
> > > Just to be sure: vddc is associated only to sclk and vddci to mclk, right?
> > > 
> > 
> > Not exactly.  Mclk is tied to vddci (memory interface voltage), but both
> > mclk and sclk (and the core display clock) are tied to vddc (core voltage).
> > 
> > > Also, how are a new freq and a new voltage applied to the card? Are they
> > > applied simultanously or sequentially? In the second case, we must be sure
> > > to raise voltage before frequency when pushing the performances up, while we
> > > should low the frequency before lowering the voltage when we are slowing
> > > down.
> > 
> > The actual adjustments are done by a microcontroller on the GPU.  You pass a
> > set of structures defining the performance levels within the power state to
> > the microcontroller and the microcontroller handles the switching.  It takes
> > into account all of the ordering and chip state dependencies.
> 
> I was asking, just in case there was a manual control over the process and I
> would have been in a situation where the card was too near of its limits.
> 
> I changed a little something in the code yesterday and I was lucky enough to
> not have any hangs. I just want to be sure it is because of this little
> change I've made and not some obscure planets alignment. I'll test it
> further today and I'll let you know.

Well, it was only luck it seems... I'll send a patch though, since it
simplifies a couple of lines.

I'll have to continue digging.

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