[Intel-gfx] [RFC] [Patch] [DRM/I915] :Add a debufs I/F to dump the I915 register

[yakui_zhao]

On Wed, 2009-06-10 at 06:35 +0800, Jesse Barnes wrote:
> On Tue, 09 Jun 2009 15:16:53 -0700
> Eric Anholt <eric at anholt.net> wrote:
> 
> > On Mon, 2009-06-08 at 08:52 +0800, yakui_zhao wrote:
> > > On Fri, 2009-06-05 at 19:11 +0800, Eric Anholt wrote:
> > > > On Fri, 2009-06-05 at 15:45 +0800, yakui_zhao wrote:
> > > > > It is useful to get the register snapshot. 
> > > > > Add a debugfs I/F named "i915_reg" to dump the I915 register
> > > > > snapshot. And this is created under the dri/0/ of debugfs. 
> > > > > The output format is similar to what we have done in UMS mode.
> > > > 
> > > > I don't think that all the decode and formatting of these
> > > > registers should be in the kernel.  Every time I've had to mess
> > > > with register decode stuff for investigation, I've needed to
> > > > extend the decode. Instead, we should expose the raw register
> > > > values and make intel_reg_dumper in intel-gpu-tools that does the
> > > > decode of actual meaning.
> > > Sometimes we can see the register snapshot without using the
> > > intel-gpu-tools. For example: in UMS mode we often get the register
> > > snapshot several times in starting X. 
> > > 
> > > It will be good that we expose the raw register values and then
> > > they are parsed by intel-gpu-tools if we need to extend the decode.
> > > 
> > > How about adding two debugfs I/F? One is to dump the raw register
> > > snapshot(without decode and format). Another is what I have done in
> > > the patch.
> > 
> > No, I won't pull something that puts the decode in the kernel without
> > a really good argument.  Expose the register names and values.
> > 
> 
> Yakui, have you experimented with just dumping the whole mmio range?
> If that works ok we could just make intel-gpu-tools programs to
> interpret the data in a chipset specific way...
It seems that this is a good point. 
In this patch only the registers related with modesetting are dumped.

Is it ok that the whole mmio range is divided into several parts? 
a. memory interface, instruction and interrupt control registers
b. 3d debug registers
c. modeset registers(display,pipe, etc).

> 
> Jesse