drm/panfrost: Replace fdinfo's profiling debugfs knob with sysfs

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>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240306015819.822128-2-adrian.larumbe@collabora.com

diff --git a/Documentation/ABI/testing/sysfs-driver-panfrost-profiling b/Documentation/ABI/testing/sysfs-driver-panfrost-profiling
new file mode 100644 (file)
index 0000000..1d8bb09
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-panfrost-profiling
@@ -0,0 +1,10 @@
+What:          /sys/bus/platform/drivers/panfrost/.../profiling
+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: Don't enable fdinfo job profiling sources.
+               1: Enable fdinfo job profiling sources, this enables both the GPU's
+                  timestamp and cycle counter registers.
\ No newline at end of file

diff --git a/Documentation/gpu/panfrost.rst b/Documentation/gpu/panfrost.rst
index b80e41f4b2c57f05eba02278738f78ac20dd137e..51ba375fd80d0df258d49dac551ba76e382031af 100644 (file)
--- 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/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 2c01c1e7523e9fd894e5947c761438cc7a46546c..7da2b3f02ed90c526cc2770210736d67bc0cf5fc 100644 (file)
--- a/drivers/gpu/drm/panfrost/Makefile
+++ b/drivers/gpu/drm/panfrost/Makefile
@@ -12,6 +12,4 @@ panfrost-y := \
        panfrost_perfcnt.o \
        panfrost_dump.o
 
-panfrost-$(CONFIG_DEBUG_FS) += panfrost_debugfs.o
-
 obj-$(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 (file)
index 72d4286..0000000
--- 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 (file)
index c5af5f3..0000000
--- 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 62f7e35273857be642fc1f21deb80b65619ba842..cffcb0ac7c11114fbbaadcbb8f8ed3e1f1a2719b 100644 (file)
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -130,7 +130,7 @@ struct panfrost_device {
        struct list_head scheduled_jobs;
 
        struct panfrost_perfcnt *perfcnt;
-       atomic_t profile_mode;
+       bool profile_mode;
 
        struct mutex sched_lock;
 

diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
index a926d71e813137fd4320f4dd397a739df0bf0000..eec25011411492cc2c3226f403c497847f521ea7 100644 (file)
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -20,7 +20,6 @@
 #include "panfrost_job.h"
 #include "panfrost_gpu.h"
 #include "panfrost_perfcnt.h"
-#include "panfrost_debugfs.h"
 
 static bool unstable_ioctls;
 module_param_unsafe(unstable_ioctls, bool, 0600);
@@ -600,10 +599,6 @@ 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)
@@ -692,6 +687,40 @@ static void panfrost_remove(struct platform_device *pdev)
        drm_dev_put(ddev);
 }
 
+static ssize_t profiling_show(struct device *dev,
+                             struct device_attribute *attr, char *buf)
+{
+       struct panfrost_device *pfdev = dev_get_drvdata(dev);
+
+       return sysfs_emit(buf, "%d\n", pfdev->profile_mode);
+}
+
+static ssize_t profiling_store(struct device *dev,
+                              struct device_attribute *attr,
+                              const char *buf, size_t len)
+{
+       struct panfrost_device *pfdev = dev_get_drvdata(dev);
+       bool value;
+       int err;
+
+       err = kstrtobool(buf, &value);
+       if (err)
+               return err;
+
+       pfdev->profile_mode = value;
+
+       return len;
+}
+
+static DEVICE_ATTR_RW(profiling);
+
+static struct attribute *panfrost_attrs[] = {
+       &dev_attr_profiling.attr,
+       NULL,
+};
+
+ATTRIBUTE_GROUPS(panfrost);
+
 /*
  * The OPP core wants the supply names to be NULL terminated, but we need the
  * correct num_supplies value for regulator core. Hence, we NULL terminate here
@@ -789,6 +818,7 @@ static struct platform_driver panfrost_driver = {
                .name   = "panfrost",
                .pm     = pm_ptr(&panfrost_pm_ops),
                .of_match_table = dt_match,
+               .dev_groups = panfrost_groups,
        },
 };
 module_platform_driver(panfrost_driver);

diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
index 0c2dbf6ef2a554914b0306f4569477e99ae67705..a61ef0af9a4e48abe114d11e0ff2b217e2a1ec56 100644 (file)
--- 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 (pfdev->profile_mode) {
                        panfrost_cycle_counter_get(pfdev);
                        job->is_profiled = true;
                        job->start_time = ktime_get();