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From: =?UTF-8?q?Adri=C3=A1n=20Larumbe?= <adrian.larumbe@collabora.com>
To: Boris Brezillon <boris.brezillon@collabora.com>,
	Rob Herring <robh@kernel.org>,
	Steven Price <steven.price@arm.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>,
	Daniel Vetter <daniel@ffwll.ch>,
	Jonathan Corbet <corbet@lwn.net>
Cc: kernel@collabora.com,
	=?UTF-8?q?Adri=C3=A1n=20Larumbe?= <adrian.larumbe@collabora.com>,
	linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org,
	linux-doc@vger.kernel.org
Subject: [PATCH] drm/panfrost: Replace fdinfo's profiling debugfs knob with sysfs
Date: Wed, 21 Feb 2024 16:12:32 +0000
Message-ID: <20240221161237.2478193-1-adrian.larumbe@collabora.com>
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Debugfs isn't always available in production builds that try to squeeze
every single byte out of the kernel image, but we still need a way to
toggle the timestamp and cycle counter registers so that jobs can be
profiled for fdinfo's drm engine and cycle calculations.

Drop the debugfs knob and replace it with a sysfs file that accomplishes
the same functionality, and document its ABI in a separate file.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
---
 .../testing/sysfs-driver-panfrost-profiling   | 10 +++
 Documentation/gpu/panfrost.rst                |  9 +++
 drivers/gpu/drm/panfrost/Makefile             |  5 +-
 drivers/gpu/drm/panfrost/panfrost_debugfs.c   | 21 ------
 drivers/gpu/drm/panfrost/panfrost_debugfs.h   | 14 ----
 drivers/gpu/drm/panfrost/panfrost_device.h    |  5 +-
 drivers/gpu/drm/panfrost/panfrost_drv.c       | 14 ++--
 drivers/gpu/drm/panfrost/panfrost_job.c       |  2 +-
 drivers/gpu/drm/panfrost/panfrost_sysfs.c     | 74 +++++++++++++++++++
 drivers/gpu/drm/panfrost/panfrost_sysfs.h     | 15 ++++
 10 files changed, 124 insertions(+), 45 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-panfrost-profiling
 delete mode 100644 drivers/gpu/drm/panfrost/panfrost_debugfs.c
 delete mode 100644 drivers/gpu/drm/panfrost/panfrost_debugfs.h
 create mode 100644 drivers/gpu/drm/panfrost/panfrost_sysfs.c
 create mode 100644 drivers/gpu/drm/panfrost/panfrost_sysfs.h

diff --git a/Documentation/ABI/testing/sysfs-driver-panfrost-profiling b/Documentation/ABI/testing/sysfs-driver-panfrost-profiling
new file mode 100644
index 000000000000..ce54069714f3
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-panfrost-profiling
@@ -0,0 +1,10 @@
+What:		/sys/bus/.../drivers/panfrost/.../drm/../profiling/status
+Date:		February 2024
+KernelVersion:	6.8.0
+Contact:	Adrian Larumbe <adrian.larumbe@collabora.com>
+Description:
+                Get/set drm fdinfo's engine and cycles profiling status.
+                Valid values are:
+		0: Disable fdinfo job profiling sources. This disables both the GPU's
+                timestamp and cycle counter registers.
+		1: Enable the above.
diff --git a/Documentation/gpu/panfrost.rst b/Documentation/gpu/panfrost.rst
index b80e41f4b2c5..be4ac282ef63 100644
--- a/Documentation/gpu/panfrost.rst
+++ b/Documentation/gpu/panfrost.rst
@@ -38,3 +38,12 @@ the currently possible format options:
 
 Possible `drm-engine-` key names are: `fragment`, and  `vertex-tiler`.
 `drm-curfreq-` values convey the current operating frequency for that engine.
+
+Users must bear in mind that engine and cycle sampling are disabled by default,
+because of power saving concerns. `fdinfo` users and benchmark applications which
+query the fdinfo file must make sure to toggle the job profiling status of the
+driver by writing into the appropriate sysfs node::
+
+    echo <N> > /sys/bus/platform/drivers/panfrost/[a-f0-9]*.gpu/drm/card1/profiling
+
+Where `N` is either `0` or `1`, depending on the desired enablement status.
diff --git a/drivers/gpu/drm/panfrost/Makefile b/drivers/gpu/drm/panfrost/Makefile
index 2c01c1e7523e..6e718595d8a6 100644
--- a/drivers/gpu/drm/panfrost/Makefile
+++ b/drivers/gpu/drm/panfrost/Makefile
@@ -10,8 +10,7 @@ panfrost-y := \
 	panfrost_job.o \
 	panfrost_mmu.o \
 	panfrost_perfcnt.o \
-	panfrost_dump.o
-
-panfrost-$(CONFIG_DEBUG_FS) += panfrost_debugfs.o
+	panfrost_dump.o \
+	panfrost_sysfs.o
 
 obj-$(CONFIG_DRM_PANFROST) += panfrost.o
diff --git a/drivers/gpu/drm/panfrost/panfrost_debugfs.c b/drivers/gpu/drm/panfrost/panfrost_debugfs.c
deleted file mode 100644
index 72d4286a6bf7..000000000000
--- a/drivers/gpu/drm/panfrost/panfrost_debugfs.c
+++ /dev/null
@@ -1,21 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/* Copyright 2023 Collabora ltd. */
-/* Copyright 2023 Amazon.com, Inc. or its affiliates. */
-
-#include <linux/debugfs.h>
-#include <linux/platform_device.h>
-#include <drm/drm_debugfs.h>
-#include <drm/drm_file.h>
-#include <drm/panfrost_drm.h>
-
-#include "panfrost_device.h"
-#include "panfrost_gpu.h"
-#include "panfrost_debugfs.h"
-
-void panfrost_debugfs_init(struct drm_minor *minor)
-{
-	struct drm_device *dev = minor->dev;
-	struct panfrost_device *pfdev = platform_get_drvdata(to_platform_device(dev->dev));
-
-	debugfs_create_atomic_t("profile", 0600, minor->debugfs_root, &pfdev->profile_mode);
-}
diff --git a/drivers/gpu/drm/panfrost/panfrost_debugfs.h b/drivers/gpu/drm/panfrost/panfrost_debugfs.h
deleted file mode 100644
index c5af5f35877f..000000000000
--- a/drivers/gpu/drm/panfrost/panfrost_debugfs.h
+++ /dev/null
@@ -1,14 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Copyright 2023 Collabora ltd.
- * Copyright 2023 Amazon.com, Inc. or its affiliates.
- */
-
-#ifndef PANFROST_DEBUGFS_H
-#define PANFROST_DEBUGFS_H
-
-#ifdef CONFIG_DEBUG_FS
-void panfrost_debugfs_init(struct drm_minor *minor);
-#endif
-
-#endif  /* PANFROST_DEBUGFS_H */
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
index 62f7e3527385..56c8e5551335 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -130,7 +130,10 @@ struct panfrost_device {
 	struct list_head scheduled_jobs;
 
 	struct panfrost_perfcnt *perfcnt;
-	atomic_t profile_mode;
+	struct kobj_profiling {
+		struct kobject base;
+		atomic_t profile_mode;
+	} profiling;
 
 	struct mutex sched_lock;
 
diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
index a926d71e8131..6db1ea453514 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -20,7 +20,7 @@
 #include "panfrost_job.h"
 #include "panfrost_gpu.h"
 #include "panfrost_perfcnt.h"
-#include "panfrost_debugfs.h"
+#include "panfrost_sysfs.h"
 
 static bool unstable_ioctls;
 module_param_unsafe(unstable_ioctls, bool, 0600);
@@ -600,10 +600,6 @@ static const struct drm_driver panfrost_drm_driver = {
 
 	.gem_create_object	= panfrost_gem_create_object,
 	.gem_prime_import_sg_table = panfrost_gem_prime_import_sg_table,
-
-#ifdef CONFIG_DEBUG_FS
-	.debugfs_init		= panfrost_debugfs_init,
-#endif
 };
 
 static int panfrost_probe(struct platform_device *pdev)
@@ -663,8 +659,14 @@ static int panfrost_probe(struct platform_device *pdev)
 	if (err)
 		goto err_out2;
 
+	err = panfrost_sysfs_init(pfdev);
+	if (err)
+		goto err_out3;
+
 	return 0;
 
+err_out3:
+	panfrost_gem_shrinker_cleanup(ddev);
 err_out2:
 	drm_dev_unregister(ddev);
 err_out1:
@@ -681,6 +683,8 @@ static void panfrost_remove(struct platform_device *pdev)
 	struct panfrost_device *pfdev = platform_get_drvdata(pdev);
 	struct drm_device *ddev = pfdev->ddev;
 
+	panfrost_sysfs_cleanup(pfdev);
+
 	drm_dev_unregister(ddev);
 	panfrost_gem_shrinker_cleanup(ddev);
 
diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
index 0c2dbf6ef2a5..49413dfda2ea 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -243,7 +243,7 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
 	subslot = panfrost_enqueue_job(pfdev, js, job);
 	/* Don't queue the job if a reset is in progress */
 	if (!atomic_read(&pfdev->reset.pending)) {
-		if (atomic_read(&pfdev->profile_mode)) {
+		if (atomic_read(&pfdev->profiling.profile_mode)) {
 			panfrost_cycle_counter_get(pfdev);
 			job->is_profiled = true;
 			job->start_time = ktime_get();
diff --git a/drivers/gpu/drm/panfrost/panfrost_sysfs.c b/drivers/gpu/drm/panfrost/panfrost_sysfs.c
new file mode 100644
index 000000000000..072d3bf349d2
--- /dev/null
+++ b/drivers/gpu/drm/panfrost/panfrost_sysfs.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright 2023 Collabora ltd. */
+/* Copyright 2023 Amazon.com, Inc. or its affiliates. */
+
+#include <linux/platform_device.h>
+#include <drm/drm_file.h>
+#include <drm/panfrost_drm.h>
+
+#include "panfrost_device.h"
+#include "panfrost_gpu.h"
+#include "panfrost_sysfs.h"
+
+static ssize_t
+profiling_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+	atomic_t *profile_mode =
+		&container_of(kobj, struct {
+			struct kobject base;
+			atomic_t profile_mode; },
+			base)->profile_mode;
+
+	return sysfs_emit(buf, "%d\n", atomic_read(profile_mode));
+}
+
+static ssize_t
+profiling_store(struct kobject *kobj, struct kobj_attribute *attr,
+	       const char *buf, size_t count)
+{
+	atomic_t *profile_mode =
+		&container_of(kobj, struct {
+			struct kobject base;
+			atomic_t profile_mode; },
+			base)->profile_mode;
+	int err, value;
+
+	err = kstrtoint(buf, 0, &value);
+	if (err)
+		return err;
+
+	atomic_set(profile_mode, !!value);
+
+	return count;
+}
+
+static const struct kobj_attribute profiling_status =
+__ATTR(status, 0644, profiling_show, profiling_store);
+
+static const struct kobj_type kobj_profile_type = {
+	.sysfs_ops = &kobj_sysfs_ops,
+};
+
+int panfrost_sysfs_init(struct panfrost_device *pfdev)
+{
+	struct device *kdev = pfdev->ddev->primary->kdev;
+	int err;
+
+	kobject_init(&pfdev->profiling.base, &kobj_profile_type);
+
+	err = kobject_add(&pfdev->profiling.base, &kdev->kobj, "%s", "profiling");
+	if (err)
+		return err;
+
+	err = sysfs_create_file(&pfdev->profiling.base, &profiling_status.attr);
+	if (err)
+		kobject_del(&pfdev->profiling.base);
+
+	return err;
+}
+
+void panfrost_sysfs_cleanup(struct panfrost_device *pfdev)
+{
+	sysfs_remove_file(&pfdev->profiling.base, &profiling_status.attr);
+	kobject_del(&pfdev->profiling.base);
+}
diff --git a/drivers/gpu/drm/panfrost/panfrost_sysfs.h b/drivers/gpu/drm/panfrost/panfrost_sysfs.h
new file mode 100644
index 000000000000..5fc9c8c1091a
--- /dev/null
+++ b/drivers/gpu/drm/panfrost/panfrost_sysfs.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2023 Collabora ltd.
+ * Copyright 2023 Amazon.com, Inc. or its affiliates.
+ */
+
+#ifndef PANFROST_SYSFS_H
+#define PANFROST_SYSFS_H
+
+struct panfrost_device;
+
+int panfrost_sysfs_init(struct panfrost_device *pfdev);
+void panfrost_sysfs_cleanup(struct panfrost_device *pfdev);
+
+#endif  /* PANFROST_SYSFS_H */
-- 
2.43.0