need guidance re amdgpu i2c

[Sanford Rockowitz]

First, apologies in advance if this is not the most appropriate list for
my questions.  Redirection appreciated.

I am the author of ddctool <www.ddctool.com>, a utility to manipulate
monitor settings using DDC/CI over I2C.

My understanding is that amdgpu provides /dev/i2c-* devices in the usual
way, so that ddctool should just work without changes.  But of course
this needs to be tested.

In this regard I have a number of questions and a request.

Does the i2c interface depend in some way on whether one is running the
AMDGPU-PRO driver?

The most current AMD card that I own in a R9 280, which is a first
generation GCN device.   Phoronix suggests that first generation GCN
support is in the works.  Will this be soon?   If not, would the current
development code for amdgpu be sufficient for me to test the i2c
support?   If so, what would I have to do to build and install it?

Or should I just plunk down a few dollars for a relatively inexpensive
R7 260, which I understand is supported by the current amdgpu?

Alternatively, if someone running the amdgpu driver would be willing to
install and test ddctool on their system I'd be most appreciative.  The
git repository is here: https://github.com/rockowitz/ddctool, and
there's extensive documentation on the website, www.ddctool.com.

A couple of command line options of note:

  "--stats" reports extensive performance statistics, including counts
of i2c retries required
  "--ddc"  reports DDC protocol data errors

If ddctool installs but does not seem to be working, command "ddctool
environment" may provide some clues.

Finally, the "ddctool interrogate" command fully exercises ddctool and
probes the i2c environment.  Depending on permissions, running it as
root may provide additional detail.  If you can capture the output and
send it to me that would be most helpful. 

Thanks in advance,
Sanford Rockowitz

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