Re: [PATCH 08/15] drm/i915: Expose engine properties via sysfs

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 14/10/2019 10:07, 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
>          │   ├── known_capabilities
>          │   └── name
>          ├── rcs0
>          │   ├── capabilities
>          │   ├── class
>          │   ├── instance
>          │   ├── known_capabilities
>          │   └── name
>          ├── vcs0
>          │   ├── capabilities
>          │   ├── class
>          │   ├── instance
>          │   ├── known_capabilities
>          │   └── name
>          └── vecs0
>              ├── capabilities
>              ├── class
>              ├── instance
>              ├── known_capabilities
>              └── name
> 
> v2: Include stringified capabilities
> v3: Include all known capabilities for futureproofing.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>   drivers/gpu/drm/i915/Makefile                |   3 +-
>   drivers/gpu/drm/i915/gt/intel_engine_sysfs.c | 223 +++++++++++++++++++
>   drivers/gpu/drm/i915/gt/intel_engine_sysfs.h |  14 ++
>   drivers/gpu/drm/i915/i915_sysfs.c            |   3 +
>   4 files changed, 242 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..4e403a1b069a
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c
> @@ -0,0 +1,223 @@
> +/*
> + * 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 const char * const vcs_caps[] = {
> +	[ilog2(I915_VIDEO_CLASS_CAPABILITY_HEVC)] = "hevc",
> +	[ilog2(I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC)] = "sfc",
> +};
> +static const char * const vecs_caps[] = {
> +	[ilog2(I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC)] = "sfc",
> +};
> +
> +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)
> +{
> +	struct intel_engine_cs *engine = kobj_to_engine(kobj);
> +	const char * const *repr;
> +	int num_repr, n;
> +	ssize_t len;
> +
> +	switch (engine->class) {
> +	case VIDEO_DECODE_CLASS:
> +		repr = vcs_caps;
> +		num_repr = ARRAY_SIZE(vcs_caps);
> +		break;
> +
> +	case VIDEO_ENHANCEMENT_CLASS:
> +		repr = vecs_caps;
> +		num_repr = ARRAY_SIZE(vecs_caps);
> +		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 (GEM_WARN_ON(n >= num_repr || !repr[n]))
> +			len += snprintf(buf + len, PAGE_SIZE - len,
> +					"[%x] ", n);
> +		else
> +			len += snprintf(buf + len, PAGE_SIZE - len,
> +					"%s ", repr[n]);
> +		if (GEM_WARN_ON(len >= PAGE_SIZE))
> +			break;
> +	}
> +	return repr_trim(buf, len);
> +}
> +
> +static struct kobj_attribute caps_attr =
> +__ATTR(capabilities, 0444, caps_show, NULL);
> +
> +static ssize_t
> +all_caps_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
> +{
> +	struct intel_engine_cs *engine = kobj_to_engine(kobj);
> +	const char * const *repr;
> +	int num_repr, n;
> +	ssize_t len;
> +
> +	switch (engine->class) {
> +	case VIDEO_DECODE_CLASS:
> +		repr = vcs_caps;
> +		num_repr = ARRAY_SIZE(vcs_caps);
> +		break;
> +
> +	case VIDEO_ENHANCEMENT_CLASS:
> +		repr = vecs_caps;
> +		num_repr = ARRAY_SIZE(vecs_caps);
> +		break;
> +
> +	default:
> +		repr = NULL;
> +		num_repr = 0;
> +		break;
> +	}
> +
> +	len = 0;
> +	for (n = 0; n < num_repr; n++) {
> +		if (!repr[n])
> +			continue;
> +
> +		len += snprintf(buf + len, PAGE_SIZE - len, "%s ", repr[n]);
> +		if (GEM_WARN_ON(len >= PAGE_SIZE))
> +			break;
> +	}
> +	return repr_trim(buf, len);
> +}

Would it be worth consolidating like:

__caps_show(engine, buf, len, mask, warn_unknown)
{
...
	switch(engine->class...
...
	for_each_set_bit(...mask...) {
		if (n >= repr || !repr[n]) {
			if (warn_unknown)
				GEM_WARN_ON(...);
			else
				len += snprinf...
		} else {
			len += snprintf...
		}
	}
...
}

caps_show()
{
...
	len = __caps_show(engine, buf, len, engine->uabi_capabilities, true);
...
}

all_caps_show()
{
...
	len = __caps_show(engine, buf, len, ~0, false);
...
}

Regards,

Tvrtko

> +
> +static struct kobj_attribute all_caps_attr =
> +__ATTR(known_capabilities, 0444, all_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,
> +		&all_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_object;
> +
> +		if (0) {
> +err_object:
> +			kobject_put(kobj);
> +err_engine:
> +			dev_err(kdev, "Failed to add sysfs engine '%s'\n",
> +				engine->name);
> +			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)
> 
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