[RFC v2 1/1] drm/lima: Add optional devfreq support

From: Martin Blumenstingl
Date: Fri Dec 27 2019 - 12:37:59 EST

Most platforms with a Mali-400 or Mali-450 GPU also have support for
changing the GPU clock frequency. Add devfreq support so the GPU clock
rate is updated based on the actual GPU usage when the
"operating-points-v2" property is present in the board.dts.

The actual devfreq code is taken from panfrost_devfreq.c and modified so
it matches what the lima hardware needs:
- a call to dev_pm_opp_set_clkname() during initialization because there
are two clocks on Mali-4x0 IPs. "core" is the one that actually clocks
the GPU so we need to control it using devfreq.
- locking when reading or writing the devfreq statistics because (unlike
than panfrost) we have multiple PP and GP IRQs which may finish jobs
concurrently.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
---
drivers/gpu/drm/lima/Kconfig | 1 +
drivers/gpu/drm/lima/Makefile | 3 +-
drivers/gpu/drm/lima/lima_devfreq.c | 183 ++++++++++++++++++++++++++++
drivers/gpu/drm/lima/lima_devfreq.h | 15 +++
drivers/gpu/drm/lima/lima_device.c | 4 +
drivers/gpu/drm/lima/lima_device.h | 17 +++
drivers/gpu/drm/lima/lima_drv.c | 14 ++-
drivers/gpu/drm/lima/lima_sched.c | 7 ++
drivers/gpu/drm/lima/lima_sched.h | 3 +
9 files changed, 244 insertions(+), 3 deletions(-)
create mode 100644 drivers/gpu/drm/lima/lima_devfreq.c
create mode 100644 drivers/gpu/drm/lima/lima_devfreq.h

diff --git a/drivers/gpu/drm/lima/Kconfig b/drivers/gpu/drm/lima/Kconfig
index 571dc369a7e9..cdd24b68b5d4 100644
--- a/drivers/gpu/drm/lima/Kconfig
+++ b/drivers/gpu/drm/lima/Kconfig
@@ -10,5 +10,6 @@ config DRM_LIMA
depends on OF
select DRM_SCHED
select DRM_GEM_SHMEM_HELPER
+ select PM_DEVFREQ
help
DRM driver for ARM Mali 400/450 GPUs.
diff --git a/drivers/gpu/drm/lima/Makefile b/drivers/gpu/drm/lima/Makefile
index a85444b0a1d4..5e5c29875e9c 100644
--- a/drivers/gpu/drm/lima/Makefile
+++ b/drivers/gpu/drm/lima/Makefile
@@ -14,6 +14,7 @@ lima-y := \
lima_sched.o \
lima_ctx.o \
lima_dlbu.o \
- lima_bcast.o
+ lima_bcast.o \
+ lima_devfreq.o

obj-$(CONFIG_DRM_LIMA) += lima.o
diff --git a/drivers/gpu/drm/lima/lima_devfreq.c b/drivers/gpu/drm/lima/lima_devfreq.c
new file mode 100644
index 000000000000..a5fd6b8faa77
--- /dev/null
+++ b/drivers/gpu/drm/lima/lima_devfreq.c
@@ -0,0 +1,183 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
+ *
+ * Based on panfrost_devfreq.c:
+ * Copyright 2019 Collabora ltd.
+ */
+#include <linux/clk.h>
+#include <linux/devfreq.h>
+#include <linux/devfreq_cooling.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+
+#include "lima_device.h"
+#include "lima_devfreq.h"
+
+static void lima_devfreq_update_utilization(struct lima_device *ldev)
+{
+ unsigned long irqflags;
+ ktime_t now, last;
+
+ if (!ldev->devfreq.devfreq)
+ return;
+
+ spin_lock_irqsave(&ldev->devfreq.lock, irqflags);
+
+ now = ktime_get();
+ last = ldev->devfreq.time_last_update;
+
+ if (atomic_read(&ldev->devfreq.busy_count) > 0)
+ ldev->devfreq.busy_time += ktime_sub(now, last);
+ else
+ ldev->devfreq.idle_time += ktime_sub(now, last);
+
+ ldev->devfreq.time_last_update = now;
+
+ spin_unlock_irqrestore(&ldev->devfreq.lock, irqflags);
+}
+
+static int lima_devfreq_target(struct device *dev, unsigned long *freq,
+ u32 flags)
+{
+ struct dev_pm_opp *opp;
+ int err;
+
+ opp = devfreq_recommended_opp(dev, freq, flags);
+ if (IS_ERR(opp))
+ return PTR_ERR(opp);
+ dev_pm_opp_put(opp);
+
+ err = dev_pm_opp_set_rate(dev, *freq);
+ if (err)
+ return err;
+
+ return 0;
+}
+
+static void lima_devfreq_reset(struct lima_device *ldev)
+{
+ unsigned long irqflags;
+
+ spin_lock_irqsave(&ldev->devfreq.lock, irqflags);
+
+ ldev->devfreq.busy_time = 0;
+ ldev->devfreq.idle_time = 0;
+ ldev->devfreq.time_last_update = ktime_get();
+
+ spin_unlock_irqrestore(&ldev->devfreq.lock, irqflags);
+}
+
+static int lima_devfreq_get_dev_status(struct device *dev,
+ struct devfreq_dev_status *status)
+{
+ struct lima_device *ldev = dev_get_drvdata(dev);
+ unsigned long irqflags;
+
+ lima_devfreq_update_utilization(ldev);
+
+ status->current_frequency = clk_get_rate(ldev->clk_gpu);
+
+ spin_lock_irqsave(&ldev->devfreq.lock, irqflags);
+
+ status->total_time = ktime_to_ns(ktime_add(ldev->devfreq.busy_time,
+ ldev->devfreq.idle_time));
+ status->busy_time = ktime_to_ns(ldev->devfreq.busy_time);
+
+ spin_unlock_irqrestore(&ldev->devfreq.lock, irqflags);
+
+ lima_devfreq_reset(ldev);
+
+ dev_dbg(ldev->dev, "busy %lu total %lu %lu %% freq %lu MHz\n",
+ status->busy_time, status->total_time,
+ status->busy_time / (status->total_time / 100),
+ status->current_frequency / 1000 / 1000);
+
+ return 0;
+}
+
+static struct devfreq_dev_profile lima_devfreq_profile = {
+ .polling_ms = 50, /* ~3 frames */
+ .target = lima_devfreq_target,
+ .get_dev_status = lima_devfreq_get_dev_status,
+};
+
+int lima_devfreq_init(struct lima_device *ldev)
+{
+ struct thermal_cooling_device *cooling;
+ struct device *dev = &ldev->pdev->dev;
+ struct devfreq *devfreq;
+ struct dev_pm_opp *opp;
+ unsigned long cur_freq;
+ int ret;
+
+ spin_lock_init(&ldev->devfreq.lock);
+
+ ldev->devfreq.opp_table = dev_pm_opp_set_clkname(dev, "core");
+ if (IS_ERR(ldev->devfreq.opp_table))
+ return PTR_ERR(ldev->devfreq.opp_table);
+
+ ret = dev_pm_opp_of_add_table(dev);
+ if (ret == -ENODEV) /* Optional, continue without devfreq */
+ return 0;
+ else if (ret)
+ return ret;
+
+ lima_devfreq_reset(ldev);
+
+ cur_freq = clk_get_rate(ldev->clk_gpu);
+
+ opp = devfreq_recommended_opp(dev, &cur_freq, 0);
+ if (IS_ERR(opp))
+ return PTR_ERR(opp);
+
+ lima_devfreq_profile.initial_freq = cur_freq;
+ dev_pm_opp_put(opp);
+
+ devfreq = devm_devfreq_add_device(dev, &lima_devfreq_profile,
+ DEVFREQ_GOV_SIMPLE_ONDEMAND, NULL);
+ if (IS_ERR(devfreq)) {
+ dev_err(dev, "Couldn't initialize GPU devfreq\n");
+ dev_pm_opp_of_remove_table(dev);
+ return PTR_ERR(devfreq);
+ }
+
+ ldev->devfreq.devfreq = devfreq;
+
+ cooling = of_devfreq_cooling_register(dev->of_node, devfreq);
+ if (IS_ERR(cooling))
+ dev_info(dev, "Failed to register cooling device\n");
+ else
+ ldev->devfreq.cooling = cooling;
+
+ return 0;
+}
+
+void lima_devfreq_fini(struct lima_device *ldev)
+{
+ if (ldev->devfreq.cooling)
+ devfreq_cooling_unregister(ldev->devfreq.cooling);
+
+ if (ldev->devfreq.opp_table) {
+ dev_pm_opp_put_clkname(ldev->devfreq.opp_table);
+ ldev->devfreq.opp_table = NULL;
+ }
+
+ dev_pm_opp_of_remove_table(&ldev->pdev->dev);
+}
+
+void lima_devfreq_record_busy(struct lima_device *ldev)
+{
+ lima_devfreq_update_utilization(ldev);
+ atomic_inc(&ldev->devfreq.busy_count);
+}
+
+void lima_devfreq_record_idle(struct lima_device *ldev)
+{
+ int count;
+
+ lima_devfreq_update_utilization(ldev);
+ count = atomic_dec_if_positive(&ldev->devfreq.busy_count);
+ WARN_ON(count < 0);
+}
diff --git a/drivers/gpu/drm/lima/lima_devfreq.h b/drivers/gpu/drm/lima/lima_devfreq.h
new file mode 100644
index 000000000000..fe4f8a437033
--- /dev/null
+++ b/drivers/gpu/drm/lima/lima_devfreq.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright 2019 Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx> */
+
+#ifndef __LIMA_DEVFREQ_H__
+#define __LIMA_DEVFREQ_H__
+
+struct lima_device;
+
+int lima_devfreq_init(struct lima_device *ldev);
+void lima_devfreq_fini(struct lima_device *ldev);
+
+void lima_devfreq_record_busy(struct lima_device *ldev);
+void lima_devfreq_record_idle(struct lima_device *ldev);
+
+#endif
diff --git a/drivers/gpu/drm/lima/lima_device.c b/drivers/gpu/drm/lima/lima_device.c
index 19829b543024..7f1f7a1c03e5 100644
--- a/drivers/gpu/drm/lima/lima_device.c
+++ b/drivers/gpu/drm/lima/lima_device.c
@@ -214,6 +214,8 @@ static int lima_init_gp_pipe(struct lima_device *dev)
struct lima_sched_pipe *pipe = dev->pipe + lima_pipe_gp;
int err;

+ pipe->ldev = dev;
+
err = lima_sched_pipe_init(pipe, "gp");
if (err)
return err;
@@ -244,6 +246,8 @@ static int lima_init_pp_pipe(struct lima_device *dev)
struct lima_sched_pipe *pipe = dev->pipe + lima_pipe_pp;
int err, i;

+ pipe->ldev = dev;
+
err = lima_sched_pipe_init(pipe, "pp");
if (err)
return err;
diff --git a/drivers/gpu/drm/lima/lima_device.h b/drivers/gpu/drm/lima/lima_device.h
index 31158d86271c..26f0efdd17f1 100644
--- a/drivers/gpu/drm/lima/lima_device.h
+++ b/drivers/gpu/drm/lima/lima_device.h
@@ -5,6 +5,7 @@
#define __LIMA_DEVICE_H__

#include <drm/drm_device.h>
+#include <linux/atomic.h>
#include <linux/delay.h>

#include "lima_sched.h"
@@ -94,6 +95,22 @@ struct lima_device {

u32 *dlbu_cpu;
dma_addr_t dlbu_dma;
+
+ struct {
+ struct devfreq *devfreq;
+ struct opp_table *opp_table;
+ struct thermal_cooling_device *cooling;
+ ktime_t busy_time;
+ ktime_t idle_time;
+ ktime_t time_last_update;
+ atomic_t busy_count;
+ /*
+ * Protect busy_time, idle_time and time_last_update because
+ * these can be updated concurrently - for example by the GP
+ * and PP interrupts.
+ */
+ spinlock_t lock;
+ } devfreq;
};

static inline struct lima_device *
diff --git a/drivers/gpu/drm/lima/lima_drv.c b/drivers/gpu/drm/lima/lima_drv.c
index 124efe4fa97b..b64b1777f220 100644
--- a/drivers/gpu/drm/lima/lima_drv.c
+++ b/drivers/gpu/drm/lima/lima_drv.c
@@ -10,6 +10,7 @@
#include <drm/drm_prime.h>
#include <drm/lima_drm.h>

+#include "lima_devfreq.h"
#include "lima_drv.h"
#include "lima_gem.h"
#include "lima_vm.h"
@@ -296,18 +297,26 @@ static int lima_pdev_probe(struct platform_device *pdev)
if (err)
goto err_out1;

+ err = lima_devfreq_init(ldev);
+ if (err) {
+ dev_err(&pdev->dev, "Fatal error during devfreq init\n");
+ goto err_out2;
+ }
+
/*
* Register the DRM device with the core and the connectors with
* sysfs.
*/
err = drm_dev_register(ddev, 0);
if (err < 0)
- goto err_out2;
+ goto err_out3;

return 0;

-err_out2:
+err_out3:
lima_device_fini(ldev);
+err_out2:
+ lima_devfreq_fini(ldev);
err_out1:
drm_dev_put(ddev);
err_out0:
@@ -321,6 +330,7 @@ static int lima_pdev_remove(struct platform_device *pdev)
struct drm_device *ddev = ldev->ddev;

drm_dev_unregister(ddev);
+ lima_devfreq_fini(ldev);
lima_device_fini(ldev);
drm_dev_put(ddev);
lima_sched_slab_fini();
diff --git a/drivers/gpu/drm/lima/lima_sched.c b/drivers/gpu/drm/lima/lima_sched.c
index f522c5f99729..851c496a168b 100644
--- a/drivers/gpu/drm/lima/lima_sched.c
+++ b/drivers/gpu/drm/lima/lima_sched.c
@@ -5,6 +5,7 @@
#include <linux/slab.h>
#include <linux/xarray.h>

+#include "lima_devfreq.h"
#include "lima_drv.h"
#include "lima_sched.h"
#include "lima_vm.h"
@@ -213,6 +214,8 @@ static struct dma_fence *lima_sched_run_job(struct drm_sched_job *job)
*/
ret = dma_fence_get(task->fence);

+ lima_devfreq_record_busy(pipe->ldev);
+
pipe->current_task = task;

/* this is needed for MMU to work correctly, otherwise GP/PP
@@ -280,6 +283,8 @@ static void lima_sched_handle_error_task(struct lima_sched_pipe *pipe,
pipe->current_vm = NULL;
pipe->current_task = NULL;

+ lima_devfreq_record_idle(pipe->ldev);
+
drm_sched_resubmit_jobs(&pipe->base);
drm_sched_start(&pipe->base, true);
}
@@ -348,6 +353,8 @@ void lima_sched_pipe_fini(struct lima_sched_pipe *pipe)

void lima_sched_pipe_task_done(struct lima_sched_pipe *pipe)
{
+ lima_devfreq_record_idle(pipe->ldev);
+
if (pipe->error)
schedule_work(&pipe->error_work);
else {
diff --git a/drivers/gpu/drm/lima/lima_sched.h b/drivers/gpu/drm/lima/lima_sched.h
index 928af91c1118..9ae7df7d7fbb 100644
--- a/drivers/gpu/drm/lima/lima_sched.h
+++ b/drivers/gpu/drm/lima/lima_sched.h
@@ -6,6 +6,7 @@

#include <drm/gpu_scheduler.h>

+struct lima_device;
struct lima_vm;

struct lima_sched_task {
@@ -41,6 +42,8 @@ struct lima_sched_pipe {
u32 fence_seqno;
spinlock_t fence_lock;

+ struct lima_device *ldev;
+
struct lima_sched_task *current_task;
struct lima_vm *current_vm;

--
2.24.1