On 16/11/2017 16:00, Lionel Landwerlin wrote:
This enables userspace to discover the engines available on the GPU.
Here is the layout :

/sys/devices/pci0000:00/0000:00:02.0/drm/card0/engines
├── bcs0
│   ├── class
│   └── instance
├── rcs0
│   ├── class
│   └── instance
├── vcs0
│   ├── class
│   ├── hevc

For engine capabilities I was considering two alternatives since I think both would be better than stuffing individual files on the same level as class and instance.

Option 1:

$ cat vcs0/capabilities
hevc

Essentially a list of tokens similar to the cpu info string in /proc/cpuinfo.

Option 2, more subdirectories:

$ ls -1 vcs0/capabilities
hevc

Option 2 might be easier for userspace to parse? But more annoying to implement in i915 I think. So not sure.

Otherwise I am quite happy with the sysfs approach. Can't think of any real downsides at the moment.

Regards,

Tvrtko

│   └── instance
├── vcs1
│   ├── class
│   └── instance
└── vecs0
     ├── class
     └── instance

Further capabilities can be added later as attributes of each engine.

Signed-off-by: Lionel Landwerlin <lionel.g.landwer...@intel.com>
---
  drivers/gpu/drm/i915/i915_drv.h         |  1 +
  drivers/gpu/drm/i915/i915_sysfs.c       | 92 +++++++++++++++++++++++++++++++++
  drivers/gpu/drm/i915/intel_ringbuffer.h |  2 +
  3 files changed, 95 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 44b807421af8..c4f6e8ecf212 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2749,6 +2749,7 @@ struct drm_i915_private {
struct {
                struct intel_topology_kobject kobj;
+               struct kobject engines_kobj;
struct sysfs_slice {
                        struct intel_slice_kobject kobj;
diff --git a/drivers/gpu/drm/i915/i915_sysfs.c 
b/drivers/gpu/drm/i915/i915_sysfs.c
index 1d835f164d80..992aeaa91565 100644
--- a/drivers/gpu/drm/i915/i915_sysfs.c
+++ b/drivers/gpu/drm/i915/i915_sysfs.c
@@ -712,6 +712,92 @@ static void i915_teardown_topology_sysfs(struct 
drm_i915_private *dev_priv)
        kobject_del(&topology_kobj->kobj);
  }
+static struct attribute engine_instance_attr = {
+       .name = "instance",
+       .mode = 0444,
+};
+
+static struct attribute engine_class_attr = {
+       .name = "class",
+       .mode = 0444,
+};
+
+static struct attribute engine_hevc_attr = {
+       .name = "hevc",
+       .mode = 0444,
+};
+
+static ssize_t
+show_engine_attr(struct kobject *kobj, struct attribute *attr, char *buf)
+{
+       struct intel_engine_cs *engine =
+               container_of(kobj, struct intel_engine_cs, kobj);
+
+       if (attr == &engine_instance_attr)
+               return sprintf(buf, "%hhu\n", engine->uabi_id);
+       if (attr == &engine_class_attr)
+               return sprintf(buf, "%hhu\n", engine->uabi_class);
+       if (attr == &engine_hevc_attr)
+               return sprintf(buf, "%i\n", INTEL_GEN(engine->i915) >= 8);
+       return sprintf(buf, "\n");
+}
+
+static const struct sysfs_ops engine_ops = {
+       .show = show_engine_attr,
+};
+
+static struct kobj_type engine_type = {
+       .sysfs_ops = &engine_ops,
+};
+
+static int i915_setup_engines_sysfs(struct drm_i915_private *dev_priv)
+{
+       struct intel_engine_cs *engine;
+       enum intel_engine_id id;
+
+       kobject_init_and_add(&dev_priv->topology.engines_kobj,
+                            dev_priv->drm.primary->kdev->kobj.ktype,
+                            &dev_priv->drm.primary->kdev->kobj,
+                            "engines");
+
+       for_each_engine(engine, dev_priv, id) {
+               int ret;
+
+               kobject_init_and_add(&engine->kobj, &engine_type,
+                                    &dev_priv->topology.engines_kobj,
+                                    engine->name);
+
+               ret = sysfs_create_file(&engine->kobj, &engine_instance_attr);
+               if (ret)
+                       return ret;
+               ret = sysfs_create_file(&engine->kobj, &engine_class_attr);
+               if (ret)
+                       return ret;
+               if (engine->id == VCS) {
+                       ret = sysfs_create_file(&engine->kobj, 
&engine_hevc_attr);
+                       if (ret)
+                               return ret;
+               }
+       }
+
+       return 0;
+}
+
+static void i915_teardown_engines_sysfs(struct drm_i915_private *dev_priv)
+{
+       struct intel_engine_cs *engine;
+       enum intel_engine_id id;
+
+       for_each_engine(engine, dev_priv, id) {
+               sysfs_remove_file(&engine->kobj, &engine_instance_attr);
+               sysfs_remove_file(&engine->kobj, &engine_class_attr);
+               sysfs_remove_file(&engine->kobj, &engine_hevc_attr);
+       }
+
+       kobject_get(&dev_priv->topology.engines_kobj);
+       kobject_del(&dev_priv->topology.engines_kobj);
+}
+
  void i915_setup_sysfs(struct drm_i915_private *dev_priv)
  {
        struct device *kdev = dev_priv->drm.primary->kdev;
@@ -762,6 +848,10 @@ void i915_setup_sysfs(struct drm_i915_private *dev_priv)
        if (ret)
                DRM_ERROR("Topology sysfs setup failed\n");
+ ret = i915_setup_engines_sysfs(dev_priv);
+       if (ret)
+               DRM_ERROR("Engines sysfs setup failed\n");
+
        i915_setup_error_capture(kdev);
  }
@@ -771,6 +861,8 @@ void i915_teardown_sysfs(struct drm_i915_private *dev_priv) i915_teardown_error_capture(kdev); + i915_teardown_engines_sysfs(dev_priv);
+
        i915_teardown_topology_sysfs(dev_priv);
if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h 
b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 5f96533e5341..0243a9e620da 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -290,6 +290,8 @@ struct intel_engine_cs {
        struct drm_i915_private *i915;
        char name[INTEL_ENGINE_CS_MAX_NAME];
+ struct kobject kobj;
+
        enum intel_engine_id id;
        unsigned int hw_id;
        unsigned int guc_id;

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