Re: Information resources

[Phillip Susi <psusi@cfl.rr.com>]

On 02/25/2011 03:56 PM, Dave Airlie wrote:
> So you made an assumpution you knew how graphics cards worked and
> derived a theory, unfortunately the assumption was wrong.

How so?  After studying the R600 documentation I found, it sounds like 
whatever microcode is in that firmware image is constantly running, 
trying to process input from the ring buffer.  Perhaps you could point 
me to more documentation to read, as the one I found seemed to be geared 
more towards GPGPU programming.

> 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.

If it were actually doing nothing ( as opposed to busy waiting ), then 
it wouldn't be hammering the memory bus full tilt.

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

How so?  The memory interface feeds requested data to the CP, so if it 
isn't running...

> 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.

Could you point me to this documentation?