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[Dave Airlie]

On Fri, 2011-02-25 at 15:42 -0500, Phillip Susi wrote:
> On 2/25/2011 3:03 PM, Dave Airlie wrote:
> > How do you know its running in an infinite loop?
> 
> Because the gpu temperature is rising to over 80 C, so it is busy doing
> something.  And this is booting with init=/bin/bash, so NOTHING is
> running that could be keeping it busy.

So you made an assumpution you knew how graphics cards worked and
derived a theory, unfortunately the assumption was wrong.

a GPU doing nothing still runs at a high clock speed, clocking the
memory bus for the video RAM at full tilt. We don't have reliably
dynamic power management yet so at the moment manual clock switching is
all we have.

Even if the CP was running in a tight loop it consumes no power compared
to the memory interfaces.

> 
> I had been under the impression that since ati/amd started releasing
> documentation a few years ago that the mesa driver had managed to
> implement its own firmware.  I sounds more like it has ripped the
> firmware out of the proprietary driver and reverse engineered the interface?

Yes and no. AMD supplied firmware from their driver with the interfaces
documented like they have done since r100. You could write your own
microcode after you RE and write an assembler for the CP core, but so
far nobody has done this and we have a lot of other areas to improve
before most of the developers would care.

Dave.