Every thing related to devfreq in placed in panthor_devfreq.c, and
helpers that can be called by other logical blocks are exposed through
panthor_devfreq.h.
This implementation is loosely based on the panfrost implementation,
the only difference being that we don't count device users, because
the idle/active state will be managed by the scheduler logic.
v2:
- Added in v2
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
---
drivers/gpu/drm/panthor/panthor_devfreq.c | 281 ++++++++++++++++++++++
drivers/gpu/drm/panthor/panthor_devfreq.h | 25 ++
2 files changed, 306 insertions(+)
create mode 100644 drivers/gpu/drm/panthor/panthor_devfreq.c
create mode 100644 drivers/gpu/drm/panthor/panthor_devfreq.h
diff --git a/drivers/gpu/drm/panthor/panthor_devfreq.c b/drivers/gpu/drm/panthor/panthor_devfreq.c
new file mode 100644
index 000000000000..500ce34cccc2
--- /dev/null
+++ b/drivers/gpu/drm/panthor/panthor_devfreq.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: GPL-2.0 or MIT
+/* Copyright 2019 Collabora ltd. */
+
+#include <linux/clk.h>
+#include <linux/devfreq.h>
+#include <linux/devfreq_cooling.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+
+#include <drm/drm_managed.h>
+
+#include "panthor_device.h"
+#include "panthor_devfreq.h"
+
+/**
+ * struct panthor_devfreq - Device frequency management
+ */
+struct panthor_devfreq {
+ /** @devfreq: devfreq device. */
+ struct devfreq *devfreq;
+
+ /** @gov_data: Governor data. */
+ struct devfreq_simple_ondemand_data gov_data;
+
+ /** @busy_time: Busy time. */
+ ktime_t busy_time;
+
+ /** @idle_time: Idle time. */
+ ktime_t idle_time;
+
+ /** @time_last_update: Last update time. */
+ ktime_t time_last_update;
+
+ /** @last_busy_state: True if the GPU was busy last time we updated the state. */
+ bool last_busy_state;
+
+ /*
+ * Protect busy_time, idle_time, time_last_update and last_busy_state
+ * because these can be accessed concurrently by panthor_devfreq_get_dev_status()
+ * and panthor_devfreq_record_{busy,idle}().
+ */
+ spinlock_t lock;
+};
+
+static void panthor_devfreq_update_utilization(struct panthor_devfreq *pdevfreq)
+{
+ ktime_t now, last;
+
+ now = ktime_get();
+ last = pdevfreq->time_last_update;
+
+ if (pdevfreq->last_busy_state)
+ pdevfreq->busy_time += ktime_sub(now, last);
+ else
+ pdevfreq->idle_time += ktime_sub(now, last);
+
+ pdevfreq->time_last_update = now;
+}
+
+static int panthor_devfreq_target(struct device *dev, unsigned long *freq,
+ u32 flags)
+{
+ struct dev_pm_opp *opp;
+
+ opp = devfreq_recommended_opp(dev, freq, flags);
+ if (IS_ERR(opp))
+ return PTR_ERR(opp);
+ dev_pm_opp_put(opp);
+
+ return dev_pm_opp_set_rate(dev, *freq);
+}
+
+static void panthor_devfreq_reset(struct panthor_devfreq *pdevfreq)
+{
+ pdevfreq->busy_time = 0;
+ pdevfreq->idle_time = 0;
+ pdevfreq->time_last_update = ktime_get();
+}
+
+static int panthor_devfreq_get_dev_status(struct device *dev,
+ struct devfreq_dev_status *status)
+{
+ struct panthor_device *ptdev = dev_get_drvdata(dev);
+ struct panthor_devfreq *pdevfreq = ptdev->devfreq;
+ unsigned long irqflags;
+
+ status->current_frequency = clk_get_rate(ptdev->clks.core);
+
+ spin_lock_irqsave(&pdevfreq->lock, irqflags);
+
+ panthor_devfreq_update_utilization(pdevfreq);
+
+ status->total_time = ktime_to_ns(ktime_add(pdevfreq->busy_time,
+ pdevfreq->idle_time));
+
+ status->busy_time = ktime_to_ns(pdevfreq->busy_time);
+
+ panthor_devfreq_reset(pdevfreq);
+
+ spin_unlock_irqrestore(&pdevfreq->lock, irqflags);
+
+ drm_dbg(&ptdev->base, "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 panthor_devfreq_profile = {
+ .timer = DEVFREQ_TIMER_DELAYED,
+ .polling_ms = 50, /* ~3 frames */
+ .target = panthor_devfreq_target,
+ .get_dev_status = panthor_devfreq_get_dev_status,
+};
+
+int panthor_devfreq_init(struct panthor_device *ptdev)
+{
+ /* There's actually 2 regulators (mali and sram), but the OPP core only
+ * supports one.
+ *
+ * We assume the sram regulator is coupled with the mali one and let
+ * the coupling logic deal with voltage updates.
+ */
+ static const char *reg_names[] = { "mali", NULL };
+ struct thermal_cooling_device *cooling;
+ struct device *dev = ptdev->base.dev;
+ struct panthor_devfreq *pdevfreq;
+ struct dev_pm_opp *opp;
+ unsigned long cur_freq;
+ int ret;
+
+ pdevfreq = drmm_kzalloc(&ptdev->base, sizeof(*ptdev->devfreq), GFP_KERNEL);
+ if (!pdevfreq)
+ return -ENOMEM;
+
+ ptdev->devfreq = pdevfreq;
+
+ ret = devm_pm_opp_set_regulators(dev, reg_names);
+ if (ret) {
+ if (ret != -EPROBE_DEFER)
+ DRM_DEV_ERROR(dev, "Couldn't set OPP regulators\n");
+
+ return ret;
+ }
+
+ ret = devm_pm_opp_of_add_table(dev);
+ if (ret)
+ return ret;
+
+ spin_lock_init(&pdevfreq->lock);
+
+ panthor_devfreq_reset(pdevfreq);
+
+ cur_freq = clk_get_rate(ptdev->clks.core);
+
+ opp = devfreq_recommended_opp(dev, &cur_freq, 0);
+ if (IS_ERR(opp))
+ return PTR_ERR(opp);
+
+ panthor_devfreq_profile.initial_freq = cur_freq;
+
+ /* Regulator coupling only takes care of synchronizing/balancing voltage
+ * updates, but the coupled regulator needs to be enabled manually.
+ *
+ * We use devm_regulator_get_enable_optional() and keep the sram supply
+ * enabled until the device is removed, just like we do for the mali
+ * supply, which is enabled when dev_pm_opp_set_opp(dev, opp) is called,
+ * and disabled when the opp_table is torn down, using the devm action.
+ *
+ * If we really care about disabling regulators on suspend, we should:
+ * - use devm_regulator_get_optional() here
+ * - call dev_pm_opp_set_opp(dev, NULL) before leaving this function
+ * (this disables the regulator passed to the OPP layer)
+ * - call dev_pm_opp_set_opp(dev, NULL) and
+ * regulator_disable(ptdev->regulators.sram) in
+ * panthor_devfreq_suspend()
+ * - call dev_pm_opp_set_opp(dev, default_opp) and
+ * regulator_enable(ptdev->regulators.sram) in
+ * panthor_devfreq_resume()
+ *
+ * But without knowing if it's beneficial or not (in term of power
+ * consumption), or how much it slows down the suspend/resume steps,
+ * let's just keep regulators enabled for the device lifetime.
+ */
+ ret = devm_regulator_get_enable_optional(dev, "sram");
+ if (ret && ret != -ENODEV) {
+ if (ret != -EPROBE_DEFER)
+ DRM_DEV_ERROR(dev, "Couldn't retrieve/enable sram supply\n");
+ return ret;
+ }
+
+ /*
+ * Set the recommend OPP this will enable and configure the regulator
+ * if any and will avoid a switch off by regulator_late_cleanup()
+ */
+ ret = dev_pm_opp_set_opp(dev, opp);
+ if (ret) {
+ DRM_DEV_ERROR(dev, "Couldn't set recommended OPP\n");
+ return ret;
+ }
+
+ dev_pm_opp_put(opp);
+
+ /*
+ * Setup default thresholds for the simple_ondemand governor.
+ * The values are chosen based on experiments.
+ */
+ pdevfreq->gov_data.upthreshold = 45;
+ pdevfreq->gov_data.downdifferential = 5;
+
+ pdevfreq->devfreq = devm_devfreq_add_device(dev, &panthor_devfreq_profile,
+ DEVFREQ_GOV_SIMPLE_ONDEMAND,
+ &pdevfreq->gov_data);
+ if (IS_ERR(pdevfreq->devfreq)) {
+ DRM_DEV_ERROR(dev, "Couldn't initialize GPU devfreq\n");
+ ret = PTR_ERR(pdevfreq->devfreq);
+ pdevfreq->devfreq = NULL;
+ return ret;
+ }
+
+ cooling = devfreq_cooling_em_register(pdevfreq->devfreq, NULL);
+ if (IS_ERR(cooling))
+ DRM_DEV_INFO(dev, "Failed to register cooling device\n");
+
+ return 0;
+}
+
+int panthor_devfreq_resume(struct panthor_device *ptdev)
+{
+ struct panthor_devfreq *pdevfreq = ptdev->devfreq;
+
+ if (!pdevfreq->devfreq)
+ return 0;
+
+ panthor_devfreq_reset(pdevfreq);
+
+ return devfreq_resume_device(pdevfreq->devfreq);
+}
+
+int panthor_devfreq_suspend(struct panthor_device *ptdev)
+{
+ struct panthor_devfreq *pdevfreq = ptdev->devfreq;
+
+ if (!pdevfreq->devfreq)
+ return 0;
+
+ return devfreq_suspend_device(pdevfreq->devfreq);
+}
+
+void panthor_devfreq_record_busy(struct panthor_device *ptdev)
+{
+ struct panthor_devfreq *pdevfreq = ptdev->devfreq;
+ unsigned long irqflags;
+
+ if (!pdevfreq->devfreq)
+ return;
+
+ spin_lock_irqsave(&pdevfreq->lock, irqflags);
+
+ panthor_devfreq_update_utilization(pdevfreq);
+ pdevfreq->last_busy_state = true;
+
+ spin_unlock_irqrestore(&pdevfreq->lock, irqflags);
+}
+
+void panthor_devfreq_record_idle(struct panthor_device *ptdev)
+{
+ struct panthor_devfreq *pdevfreq = ptdev->devfreq;
+ unsigned long irqflags;
+
+ if (!pdevfreq->devfreq)
+ return;
+
+ spin_lock_irqsave(&pdevfreq->lock, irqflags);
+
+ panthor_devfreq_update_utilization(pdevfreq);
+ pdevfreq->last_busy_state = false;
+
+ spin_unlock_irqrestore(&pdevfreq->lock, irqflags);
+}
diff --git a/drivers/gpu/drm/panthor/panthor_devfreq.h b/drivers/gpu/drm/panthor/panthor_devfreq.h
new file mode 100644
index 000000000000..875fbb5a1c1b
--- /dev/null
+++ b/drivers/gpu/drm/panthor/panthor_devfreq.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 or MIT */
+/* Copyright 2019 Collabora ltd. */
+
+#ifndef __PANTHOR_DEVFREQ_H__
+#define __PANTHOR_DEVFREQ_H__
+
+#include <linux/devfreq.h>
+#include <linux/spinlock.h>
+#include <linux/ktime.h>
+
+struct devfreq;
+struct thermal_cooling_device;
+
+struct panthor_device;
+struct panthor_devfreq;
+
+int panthor_devfreq_init(struct panthor_device *ptdev);
+
+int panthor_devfreq_resume(struct panthor_device *ptdev);
+int panthor_devfreq_suspend(struct panthor_device *ptdev);
+
+void panthor_devfreq_record_busy(struct panthor_device *ptdev);
+void panthor_devfreq_record_idle(struct panthor_device *ptdev);
+
+#endif /* __PANTHOR_DEVFREQ_H__ */
--
2.41.0
