On 09/11/17 21:29, Chris Wilson wrote:
Quoting Lionel Landwerlin (2017-11-09 09:13:03)
On 08/11/17 19:14, Chris Wilson wrote:
+/*
+ * Different engines serve different roles, and there may be more than one
+ * engine serving each role. enum drm_i915_gem_engine_class provides a
+ * classification of the role of the engine, which may be used when requesting
+ * operations to be performed on a certain subset of engines, or for providing
+ * information about that group.
+ */
+enum drm_i915_gem_engine_class {
+ I915_ENGINE_CLASS_OTHER = 0,
+ I915_ENGINE_CLASS_RENDER = 1,
+ I915_ENGINE_CLASS_COPY = 2,
+ I915_ENGINE_CLASS_VIDEO = 3,
+ I915_ENGINE_CLASS_VIDEO_ENHANCE = 4,
+};
+
I've tried to build a bit UI in GPUTop to show this.
I'm a bit skeptical about the OTHER type because if this enum is meant
to be extended, then why do we need an OTHER class? We should create new
classes instead.
Whilst OTHER is certainly a question of "why not add a define for the
new class", my 2c is that we do want an explicit INVALID enum. It
doesn't have to 0, -1 will work just fine as well, but there will be a
time either in userspace or in reporting from the kernel where we will
need to store an invalid value that is guaranteed not to map onto a real
class.
So I915_ENGINE_CLASS_INVALID = -1 ?
-Chris
Okay, so you want to use that value for userspace to say "execute this
batch buffer on whatever engine".
And in that case that's fine with me, I didn't get that would be used in
the userspace->kernel direction.
But I'm still struggling to understand why the kernel would report that
there is an "invalid" class of engine on this device, rather than
something more descriptive.
-
Lionel
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