[PATCH v3 0/4] Update Energy Model after chip binning adjusted voltages

[PATCH v3 0/4] Update Energy Model after chip binning adjusted voltages

[Lukasz Luba]

Hi all,

This is a follow-up patch aiming to add EM modification due to chip binning.
The first RFC and the discussion can be found here [1].

It uses Exynos chip driver code as a 1st user. The EM framework has been
extended to handle this use case easily, when the voltage has been changed
after setup. On my Odroid-xu4 in some OPPs I can observe ~20% power difference.
According to that data in driver tables it could be up to ~29%.

This chip binning is applicable to a lot of SoCs, so the EM framework should
make it easy to update. It uses the existing OPP and DT information to
re-calculate the new power values.

It has dependency on Exynos SoC driver.


Changes:
v3:
- updated header description patch 2/4 (Dietmar)
- removed 2 sentences from comment and adjusted in patch 3/4 (Dietmar)
- patch 4/4 re-phrased code comment (Dietmar)
- collected tags (Krzysztof, Viresh)
v2:
- removed 'ret' from error message which wasn't initialized (Christian)
v1:
- exported the OPP calculation function from the OPP/OF so it can be
  used from EM fwk (Viresh)
- refactored EM updating function to re-use common code
- added new EM function which can be used by chip device drivers which
  modify the voltage in OPPs
RFC is at [1]

Regards,
Lukasz Luba

Lukasz Luba (4):
  OPP: OF: Export dev_opp_pm_calc_power() for usage from EM
  PM: EM: Change the em_adjust_new_capacity() to re-use code
  PM: EM: Add em_dev_update_chip_binning()
  soc: samsung: exynos-asv: Update Energy Model after adjusting voltage

 drivers/opp/of.c                 |  17 +++--
 drivers/soc/samsung/exynos-asv.c |  11 +++-
 include/linux/energy_model.h     |   5 ++
 include/linux/pm_opp.h           |   8 +++
 kernel/power/energy_model.c      | 106 +++++++++++++++++++++++++------
 5 files changed, 122 insertions(+), 25 deletions(-)

-- 
2.25.1


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[PATCH v3 1/4] OPP: OF: Export dev_opp_pm_calc_power() for usage from EM

[Lukasz Luba]

There are device drivers which can modify voltage values for OPPs. It
could be due to the chip binning and those drivers have specific chip
knowledge about it. This adjustment can happen after Energy Model is
registered, thus EM can have stale data about power.

Export dev_opp_pm_calc_power() which can be used by Energy Model to
calculate new power with the new voltage for OPPs.

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
---
 drivers/opp/of.c       | 17 ++++++++++++-----
 include/linux/pm_opp.h |  8 ++++++++
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/opp/of.c b/drivers/opp/of.c
index f9f0b22bccbb4..282eb5966fd03 100644
--- a/drivers/opp/of.c
+++ b/drivers/opp/of.c
@@ -1494,20 +1494,26 @@ _get_dt_power(struct device *dev, unsigned long *uW, unsigned long *kHz)
 	return 0;
 }
 
-/*
- * Callback function provided to the Energy Model framework upon registration.
+/**
+ * dev_pm_opp_calc_power() - Calculate power value for device with EM
+ * @dev		: Device for which an Energy Model has to be registered
+ * @uW		: New power value that is calculated
+ * @kHz		: Frequency for which the new power is calculated
+ *
  * This computes the power estimated by @dev at @kHz if it is the frequency
  * of an existing OPP, or at the frequency of the first OPP above @kHz otherwise
  * (see dev_pm_opp_find_freq_ceil()). This function updates @kHz to the ceiled
  * frequency and @uW to the associated power. The power is estimated as
  * P = C * V^2 * f with C being the device's capacitance and V and f
  * respectively the voltage and frequency of the OPP.
+ * It is also used as a callback function provided to the Energy Model
+ * framework upon registration.
  *
  * Returns -EINVAL if the power calculation failed because of missing
  * parameters, 0 otherwise.
  */
-static int __maybe_unused _get_power(struct device *dev, unsigned long *uW,
-				     unsigned long *kHz)
+int dev_pm_opp_calc_power(struct device *dev, unsigned long *uW,
+			  unsigned long *kHz)
 {
 	struct dev_pm_opp *opp;
 	struct device_node *np;
@@ -1544,6 +1550,7 @@ static int __maybe_unused _get_power(struct device *dev, unsigned long *uW,
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(dev_pm_opp_calc_power);
 
 static bool _of_has_opp_microwatt_property(struct device *dev)
 {
@@ -1619,7 +1626,7 @@ int dev_pm_opp_of_register_em(struct device *dev, struct cpumask *cpus)
 		goto failed;
 	}
 
-	EM_SET_ACTIVE_POWER_CB(em_cb, _get_power);
+	EM_SET_ACTIVE_POWER_CB(em_cb, dev_pm_opp_calc_power);
 
 register_em:
 	ret = em_dev_register_perf_domain(dev, nr_opp, &em_cb, cpus, true);
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index 065a47382302c..31370deb9905f 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -476,6 +476,8 @@ struct device_node *dev_pm_opp_get_of_node(struct dev_pm_opp *opp);
 int of_get_required_opp_performance_state(struct device_node *np, int index);
 int dev_pm_opp_of_find_icc_paths(struct device *dev, struct opp_table *opp_table);
 int dev_pm_opp_of_register_em(struct device *dev, struct cpumask *cpus);
+int dev_pm_opp_calc_power(struct device *dev, unsigned long *uW,
+			  unsigned long *kHz);
 static inline void dev_pm_opp_of_unregister_em(struct device *dev)
 {
 	em_dev_unregister_perf_domain(dev);
@@ -539,6 +541,12 @@ static inline void dev_pm_opp_of_unregister_em(struct device *dev)
 {
 }
 
+static inline int dev_pm_opp_calc_power(struct device *dev, unsigned long *uW,
+			  unsigned long *kHz)
+{
+	return -EOPNOTSUPP;
+}
+
 static inline int of_get_required_opp_performance_state(struct device_node *np, int index)
 {
 	return -EOPNOTSUPP;
-- 
2.25.1


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[PATCH v3 2/4] PM: EM: Change the em_adjust_new_capacity() to re-use code

[Lukasz Luba]

Extract em_table_dup() and em_recalc_and_update() from
em_adjust_new_capacity(). Both functions will be later reused by the
'update EM due to chip binning' functionality.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
---
 kernel/power/energy_model.c | 58 +++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 19 deletions(-)

diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index 9e1c9aa399ea9..6960dd7393b2d 100644
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -674,23 +674,15 @@ void em_dev_unregister_perf_domain(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(em_dev_unregister_perf_domain);
 
-/*
- * Adjustment of CPU performance values after boot, when all CPUs capacites
- * are correctly calculated.
- */
-static void em_adjust_new_capacity(struct device *dev,
-				   struct em_perf_domain *pd,
-				   u64 max_cap)
+static struct em_perf_table __rcu *em_table_dup(struct em_perf_domain *pd)
 {
 	struct em_perf_table __rcu *em_table;
 	struct em_perf_state *ps, *new_ps;
-	int ret, ps_size;
+	int ps_size;
 
 	em_table = em_table_alloc(pd);
-	if (!em_table) {
-		dev_warn(dev, "EM: allocation failed\n");
-		return;
-	}
+	if (!em_table)
+		return NULL;
 
 	new_ps = em_table->state;
 
@@ -702,24 +694,52 @@ static void em_adjust_new_capacity(struct device *dev,
 
 	rcu_read_unlock();
 
-	em_init_performance(dev, pd, new_ps, pd->nr_perf_states);
-	ret = em_compute_costs(dev, new_ps, NULL, pd->nr_perf_states,
+	return em_table;
+}
+
+static int em_recalc_and_update(struct device *dev, struct em_perf_domain *pd,
+				struct em_perf_table __rcu *em_table)
+{
+	int ret;
+
+	ret = em_compute_costs(dev, em_table->state, NULL, pd->nr_perf_states,
 			       pd->flags);
-	if (ret) {
-		dev_warn(dev, "EM: compute costs failed\n");
-		return;
-	}
+	if (ret)
+		goto free_em_table;
 
 	ret = em_dev_update_perf_domain(dev, em_table);
 	if (ret)
-		dev_warn(dev, "EM: update failed %d\n", ret);
+		goto free_em_table;
 
 	/*
 	 * This is one-time-update, so give up the ownership in this updater.
 	 * The EM framework has incremented the usage counter and from now
 	 * will keep the reference (then free the memory when needed).
 	 */
+free_em_table:
 	em_table_free(em_table);
+	return ret;
+}
+
+/*
+ * Adjustment of CPU performance values after boot, when all CPUs capacites
+ * are correctly calculated.
+ */
+static void em_adjust_new_capacity(struct device *dev,
+				   struct em_perf_domain *pd,
+				   u64 max_cap)
+{
+	struct em_perf_table __rcu *em_table;
+
+	em_table = em_table_dup(pd);
+	if (!em_table) {
+		dev_warn(dev, "EM: allocation failed\n");
+		return;
+	}
+
+	em_init_performance(dev, pd, em_table->state, pd->nr_perf_states);
+
+	em_recalc_and_update(dev, pd, em_table);
 }
 
 static void em_check_capacity_update(void)
-- 
2.25.1


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[PATCH v3 3/4] PM: EM: Add em_dev_update_chip_binning()

[Lukasz Luba]

Add a function which allows to modify easily the EM after the new voltage
information is available. The device drivers for the chip can adjust
the voltage values after setup. The voltage for the same frequency in OPP
can be different due to chip binning. The voltage impacts the power usage
and the EM power values can be updated to reflect that.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
---
 include/linux/energy_model.h |  5 ++++
 kernel/power/energy_model.c  | 48 ++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
index 770755df852f1..d30d67c2f07cf 100644
--- a/include/linux/energy_model.h
+++ b/include/linux/energy_model.h
@@ -172,6 +172,7 @@ struct em_perf_table __rcu *em_table_alloc(struct em_perf_domain *pd);
 void em_table_free(struct em_perf_table __rcu *table);
 int em_dev_compute_costs(struct device *dev, struct em_perf_state *table,
 			 int nr_states);
+int em_dev_update_chip_binning(struct device *dev);
 
 /**
  * em_pd_get_efficient_state() - Get an efficient performance state from the EM
@@ -387,6 +388,10 @@ int em_dev_compute_costs(struct device *dev, struct em_perf_state *table,
 {
 	return -EINVAL;
 }
+static inline int em_dev_update_chip_binning(struct device *dev)
+{
+	return -EINVAL;
+}
 #endif
 
 #endif
diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index 6960dd7393b2d..e284aa335b6d0 100644
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -808,3 +808,51 @@ static void em_update_workfn(struct work_struct *work)
 {
 	em_check_capacity_update();
 }
+
+/**
+ * em_dev_update_chip_binning() - Update Energy Model after the new voltage
+				information is present in the OPPs.
+ * @dev		: Device for which the Energy Model has to be updated.
+ *
+ * This function allows to update easily the EM with new values available in
+ * the OPP framework and DT. It can be used after the chip has been properly
+ * verified by device drivers and the voltages adjusted for the 'chip binning'.
+ */
+int em_dev_update_chip_binning(struct device *dev)
+{
+	struct em_perf_table __rcu *em_table;
+	struct em_perf_domain *pd;
+	int i, ret;
+
+	if (IS_ERR_OR_NULL(dev))
+		return -EINVAL;
+
+	pd = em_pd_get(dev);
+	if (!pd) {
+		dev_warn(dev, "Couldn't find Energy Model\n");
+		return -EINVAL;
+	}
+
+	em_table = em_table_dup(pd);
+	if (!em_table) {
+		dev_warn(dev, "EM: allocation failed\n");
+		return -ENOMEM;
+	}
+
+	/* Update power values which might change due to new voltage in OPPs */
+	for (i = 0; i < pd->nr_perf_states; i++) {
+		unsigned long freq = em_table->state[i].frequency;
+		unsigned long power;
+
+		ret = dev_pm_opp_calc_power(dev, &power, &freq);
+		if (ret) {
+			em_table_free(em_table);
+			return ret;
+		}
+
+		em_table->state[i].power = power;
+	}
+
+	return em_recalc_and_update(dev, pd, em_table);
+}
+EXPORT_SYMBOL_GPL(em_dev_update_chip_binning);
-- 
2.25.1


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Re: [PATCH v3 3/4] PM: EM: Add em_dev_update_chip_binning()

[kernel test robot]

Hi Lukasz,

kernel test robot noticed the following build warnings:

[auto build test WARNING on rafael-pm/linux-next]
[also build test WARNING on krzk/for-next clk/clk-next linus/master v6.9-rc1 next-20240328]
[cannot apply to soc/for-next rafael-pm/acpi-bus rafael-pm/devprop]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Lukasz-Luba/OPP-OF-Export-dev_opp_pm_calc_power-for-usage-from-EM/20240328-165357
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
patch link:    https://lore.kernel.org/r/20240328085112.3873050-4-lukasz.luba%40arm.com
patch subject: [PATCH v3 3/4] PM: EM: Add em_dev_update_chip_binning()
config: i386-buildonly-randconfig-002-20240328 (https://download.01.org/0day-ci/archive/20240329/202403291602.UyrrrpzO-lkp@intel.com/config)
compiler: gcc-12 (Ubuntu 12.3.0-9ubuntu2) 12.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240329/202403291602.UyrrrpzO-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202403291602.UyrrrpzO-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/power/energy_model.c:814: warning: bad line:                                 information is present in the OPPs.


vim +814 kernel/power/energy_model.c

   811	
   812	/**
   813	 * em_dev_update_chip_binning() - Update Energy Model after the new voltage
 > 814					information is present in the OPPs.

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

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[PATCH v3 4/4] soc: samsung: exynos-asv: Update Energy Model after adjusting voltage

[Lukasz Luba]

When the voltage for OPPs is adjusted there is a need to also update
Energy Model framework. The EM data contains power values which depend
on voltage values. The EM structure is used for thermal (IPA governor)
and in scheduler task placement (EAS) so it should reflect the real HW
model as best as possible to operate properly.

Based on data on Exynos5422 ASV tables the maximum power difference might
be ~29%. An Odroid-XU4 (with a random sample SoC in this chip lottery)
showed power difference for some OPPs ~20%. Therefore, it's worth to
update the EM.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
---
 drivers/soc/samsung/exynos-asv.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/samsung/exynos-asv.c b/drivers/soc/samsung/exynos-asv.c
index d60af8acc3916..d6d003e3a81ab 100644
--- a/drivers/soc/samsung/exynos-asv.c
+++ b/drivers/soc/samsung/exynos-asv.c
@@ -11,6 +11,7 @@
 
 #include <linux/cpu.h>
 #include <linux/device.h>
+#include <linux/energy_model.h>
 #include <linux/errno.h>
 #include <linux/of.h>
 #include <linux/pm_opp.h>
@@ -97,9 +98,17 @@ static int exynos_asv_update_opps(struct exynos_asv *asv)
 			last_opp_table = opp_table;
 
 			ret = exynos_asv_update_cpu_opps(asv, cpu);
-			if (ret < 0)
+			if (!ret) {
+				/*
+				 * When the voltage for OPPs could be changed,
+				 * make sure to update the EM power values, to
+				 * reflect the reality and not use stale data.
+				 */
+				em_dev_update_chip_binning(cpu);
+			} else {
 				dev_err(asv->dev, "Couldn't udate OPPs for cpu%d\n",
 					cpuid);
+			}
 		}
 
 		dev_pm_opp_put_opp_table(opp_table);
-- 
2.25.1


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