[Intel-gfx] [PATCH] drm/i915: Expose engine properties via sysfs
Tvrtko Ursulin
tvrtko.ursulin at linux.intel.com
Fri Oct 11 12:16:33 UTC 2019
On 11/10/2019 12:36, Chris Wilson wrote:
> Preliminary stub to add engines underneath /sys/class/drm/cardN/, so
> that we can expose properties on each engine to the sysadmin.
>
> To start with we have basic analogues of the i915_query ioctl so that we
> can pretty print engine discovery from the shell, and flesh out the
> directory structure. Later we will add writeable sysadmin properties such
> as per-engine timeout controls.
>
> An example tree of the engine properties on Braswell:
> /sys/class/drm/card0
> └── engine
> ├── bcs0
> │ ├── capabilities
> │ ├── class
> │ ├── instance
> │ └── name
> ├── rcs0
> │ ├── capabilities
> │ ├── class
> │ ├── instance
> │ └── name
> ├── vcs0
> │ ├── capabilities
> │ ├── class
> │ ├── instance
> │ └── name
> └── vecs0
> ├── capabilities
> ├── class
> ├── instance
> └── name
>
> v2: Include stringified capabilities
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Acked-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> ---
> drivers/gpu/drm/i915/Makefile | 3 +-
> drivers/gpu/drm/i915/gt/intel_engine_sysfs.c | 177 +++++++++++++++++++
> drivers/gpu/drm/i915/gt/intel_engine_sysfs.h | 14 ++
> drivers/gpu/drm/i915/i915_sysfs.c | 3 +
> 4 files changed, 196 insertions(+), 1 deletion(-)
> create mode 100644 drivers/gpu/drm/i915/gt/intel_engine_sysfs.c
> create mode 100644 drivers/gpu/drm/i915/gt/intel_engine_sysfs.h
>
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index e791d9323b51..cd9a10ba2516 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -78,8 +78,9 @@ gt-y += \
> gt/intel_breadcrumbs.o \
> gt/intel_context.o \
> gt/intel_engine_cs.o \
> - gt/intel_engine_pool.o \
> gt/intel_engine_pm.o \
> + gt/intel_engine_pool.o \
> + gt/intel_engine_sysfs.o \
> gt/intel_engine_user.o \
> gt/intel_gt.o \
> gt/intel_gt_irq.o \
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c b/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c
> new file mode 100644
> index 000000000000..f6e4822f8928
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c
> @@ -0,0 +1,177 @@
> +/*
> + * SPDX-License-Identifier: MIT
> + *
> + * Copyright © 2019 Intel Corporation
> + */
> +
> +#include <linux/kobject.h>
> +#include <linux/sysfs.h>
> +
> +#include "i915_drv.h"
> +#include "intel_engine.h"
> +#include "intel_engine_sysfs.h"
> +
> +struct kobj_engine {
> + struct kobject base;
> + struct intel_engine_cs *engine;
> +};
> +
> +static struct intel_engine_cs *kobj_to_engine(struct kobject *kobj)
> +{
> + return container_of(kobj, struct kobj_engine, base)->engine;
> +}
> +
> +static ssize_t
> +name_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%s\n", kobj_to_engine(kobj)->name);
> +}
> +
> +static struct kobj_attribute name_attr =
> +__ATTR(name, 0444, name_show, NULL);
> +
> +static ssize_t
> +class_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%d\n", kobj_to_engine(kobj)->uabi_class);
> +}
> +
> +static struct kobj_attribute class_attr =
> +__ATTR(class, 0444, class_show, NULL);
> +
> +static ssize_t
> +inst_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%d\n", kobj_to_engine(kobj)->uabi_instance);
> +}
> +
> +static struct kobj_attribute inst_attr =
> +__ATTR(instance, 0444, inst_show, NULL);
> +
> +static ssize_t repr_trim(char *buf, ssize_t len)
> +{
> + /* Trim off the trailing space and replace with a newline */
> + if (len > PAGE_SIZE)
> + len = PAGE_SIZE;
> + if (len > 0)
> + buf[len - 1] = '\n';
> +
> + return len;
> +}
> +
> +static ssize_t
> +caps_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
> +{
> + static const char *vcs_repr[] = {
> + [ilog2(I915_VIDEO_CLASS_CAPABILITY_HEVC)] = "hevc",
> + [ilog2(I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC)] = "sfc",
> + };
> + static const char *vecs_repr[] = {
> + [ilog2(I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC)] = "sfc",
> + };
> + struct intel_engine_cs *engine = kobj_to_engine(kobj);
> + const char **repr;
> + int num_repr, n;
> + ssize_t len;
> +
> + switch (engine->class) {
> + case VIDEO_DECODE_CLASS:
> + repr = vcs_repr;
> + num_repr = ARRAY_SIZE(vcs_repr);
> + break;
> +
> + case VIDEO_ENHANCEMENT_CLASS:
> + repr = vecs_repr;
> + num_repr = ARRAY_SIZE(vecs_repr);
> + break;
> +
> + default:
> + repr = NULL;
> + num_repr = 0;
> + break;
> + }
> +
> + len = 0;
> + for_each_set_bit(n,
> + (unsigned long *)&engine->uabi_capabilities,
> + BITS_PER_TYPE(typeof(engine->uabi_capabilities))) {
> + if (n < num_repr && repr[n])
> + len += snprintf(buf + len, PAGE_SIZE - len,
> + "%s ", repr[n]);
> + else
> + len += snprintf(buf + len, PAGE_SIZE - len,
> + "[%d] ", n);
Maybe we should also add a GEM_WARN_ON to reminds us to add new caps in
here during development? Presumes some IGT to exercise this of course,
or unfortunately. :)
Minor conversation point - hex or decimal?
> + }
> + return repr_trim(buf, len);
> +}
> +
> +static struct kobj_attribute caps_attr =
> +__ATTR(capabilities, 0444, caps_show, NULL);
> +
> +static void kobj_engine_release(struct kobject *kobj)
> +{
> + kfree(kobj);
> +}
> +
> +static struct kobj_type kobj_engine_type = {
> + .release = kobj_engine_release,
> + .sysfs_ops = &kobj_sysfs_ops
> +};
> +
> +static struct kobject *
> +kobj_engine(struct kobject *dir, struct intel_engine_cs *engine)
> +{
> + struct kobj_engine *ke;
> +
> + ke = kzalloc(sizeof(*ke), GFP_KERNEL);
> + if (!ke)
> + return NULL;
> +
> + kobject_init(&ke->base, &kobj_engine_type);
> + ke->engine = engine;
> +
> + if (kobject_add(&ke->base, dir, "%s", engine->name)) {
> + kobject_put(&ke->base);
> + return NULL;
> + }
> +
> + /* xfer ownership to sysfs tree */
> + return &ke->base;
> +}
> +
> +void intel_engines_add_sysfs(struct drm_i915_private *i915)
> +{
> + static const struct attribute *files[] = {
> + &name_attr.attr,
> + &class_attr.attr,
> + &inst_attr.attr,
> + &caps_attr.attr,
> + NULL
> + };
> +
> + struct device *kdev = i915->drm.primary->kdev;
> + struct intel_engine_cs *engine;
> + struct kobject *dir;
> +
> + dir = kobject_create_and_add("engine", &kdev->kobj);
> + if (!dir)
> + return;
> +
> + for_each_uabi_engine(engine, i915) {
> + struct kobject *kobj;
> +
> + kobj = kobj_engine(dir, engine);
> + if (!kobj)
> + goto err_engine;
> +
> + if (sysfs_create_files(kobj, files))
> + goto err_engine;
Do we need to kobject_put in this case?
> +
> + if (0) {
> +err_engine:
> + dev_err(kdev, "Failed to add sysfs engine '%s'\n",
> + engine->name);
Maybe not error but warning? Driver continues to work fine but userspace
need to be aware.. hm.. tricky one.
> + break;
> + }
> + }
> +}
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_sysfs.h b/drivers/gpu/drm/i915/gt/intel_engine_sysfs.h
> new file mode 100644
> index 000000000000..ef44a745b70a
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_sysfs.h
> @@ -0,0 +1,14 @@
> +/*
> + * SPDX-License-Identifier: MIT
> + *
> + * Copyright © 2019 Intel Corporation
> + */
> +
> +#ifndef INTEL_ENGINE_SYSFS_H
> +#define INTEL_ENGINE_SYSFS_H
> +
> +struct drm_i915_private;
> +
> +void intel_engines_add_sysfs(struct drm_i915_private *i915);
> +
> +#endif /* INTEL_ENGINE_SYSFS_H */
> diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
> index bf039b8ba593..7b665f69f301 100644
> --- a/drivers/gpu/drm/i915/i915_sysfs.c
> +++ b/drivers/gpu/drm/i915/i915_sysfs.c
> @@ -30,6 +30,7 @@
> #include <linux/stat.h>
> #include <linux/sysfs.h>
>
> +#include "gt/intel_engine_sysfs.h"
> #include "gt/intel_rc6.h"
>
> #include "i915_drv.h"
> @@ -616,6 +617,8 @@ void i915_setup_sysfs(struct drm_i915_private *dev_priv)
> DRM_ERROR("RPS sysfs setup failed\n");
>
> i915_setup_error_capture(kdev);
> +
> + intel_engines_add_sysfs(dev_priv);
> }
>
> void i915_teardown_sysfs(struct drm_i915_private *dev_priv)
>
Looks fine in principle.
I am tempted to go with some of the engine->flags from the start but I
don't have an use case apart from saying that it sounds like it makes sense.
Preemption cap may make sense in conjunction with heartbeat interval to
tell userspace something more?
Busy_stats might make sense for people interested in doing perf stat?
What worries me slightly is not being able to tell if a cap is supported
just not exported, or not supported but exported, if you are able to
follow. :) Which would happen if we decided to later add something from
flags.
Regards,
Tvrtko
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