Re: [PATCH v2] drm/i915/gt: move remaining debugfs interfaces into gt

[Lucas De Marchi <lucas.de.marchi@gmail.com>]

On Thu, Oct 7, 2021 at 5:27 PM Andi Shyti <andi@etezian.org> wrote:
>
> From: Andi Shyti <andi.shyti@intel.com>
>
> The following interfaces:
>
>   i915_wedged
>   i915_forcewake_user
>   i915_gem_interrupt
>
> are dependent on gt values. Put them inside gt/ and drop the
> "i915_" prefix name. This would be the new structure:
>
>   dri/0/gt
>   |
>   +-- forcewake_user
>   |
>   +-- interrupt_info
>   |
>   \-- reset
>
> For backwards compatibility with existing igt (and the slight
> semantic difference between operating on the i915 abi entry
> points and the deep gt info):
>
>   dri/0
>   |
>   +-- i915_wedged
>   |
>   \-- i915_forcewake_user
>
> remain at the top level.
>
> Signed-off-by: Andi Shyti <andi.shyti@intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> ---
> Hi,
>
> I am reproposing this patch exactly as it was proposed initially
> where the original interfaces are kept where they have been
> originally placed. It might generate some duplicated code but,
> well, it's debugfs and I don't see any issue. In the future we
> can transform the upper interfaces to act upon all the GTs and
> provide information from all the GTs. This is, for example, how
> the sysfs interfaces will act.

NACK. We've made this mistake in the past for other debugfs files.
We don't want to do it again just to maintain 2 separate places for
one year and then finally realize we want to merge them.

>
> The reason I removed them in V1 is because igt as only user is
> not a strong reason to keep duplicated code, but as Chris
> suggested offline:
>
> "It's debugfs, igt is the primary consumer. CI has to be bridged over
> changes to the interfaces it is using in any case, as you want
> comparable results before/after the patches land.

That doesn't mean you have to copy and paste it. It may mean you
do the implementation in one of them and the other calls that implementation.
See how I did the deduplication in commit d0c560316d6f ("drm/i915:
deduplicate frequency dump on debugfs")

Alternative would be to prepare igt already and then add a Test-with:
in this patch
series.... But I think it makes more sense to support both locations
for some time and then later
remove the previous one.

Thanks
Lucas De Marchi