Hi Rafael,


On Wed, Jul 11, 2018 at 3:20 PM, Rafael J. Wysocki [off-list ref] wrote:

On Sunday, July 8, 2018 7:34:10 PM CEST Vivek Gautam wrote:

quoted

From: Sricharan R <redacted>

The smmu needs to be functional only when the respective
master's using it are active. The device_link feature
helps to track such functional dependencies, so that the
iommu gets powered when the master device enables itself
using pm_runtime. So by adapting the smmu driver for
runtime pm, above said dependency can be addressed.

This patch adds the pm runtime/sleep callbacks to the
driver and also the functions to parse the smmu clocks
from DT and enable them in resume/suspend.

Signed-off-by: Sricharan R <redacted>
Signed-off-by: Archit Taneja <redacted>
[vivek: Clock rework to request bulk of clocks]
Signed-off-by: Vivek Gautam <redacted>
Reviewed-by: Tomasz Figa <redacted>
---

 - No change since v11.

 drivers/iommu/arm-smmu.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 58 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index f7a96bcf94a6..a01d0dde21dd 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c

@@ -48,6 +48,7 @@
 #include <linux/of_iommu.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>

@@ -205,6 +206,8 @@ struct arm_smmu_device {
      u32                             num_global_irqs;
      u32                             num_context_irqs;
      unsigned int                    *irqs;
+     struct clk_bulk_data            *clks;
+     int                             num_clks;

      u32                             cavium_id_base; /* Specific to Cavium */

@@ -1897,10 +1900,12 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
 struct arm_smmu_match_data {
      enum arm_smmu_arch_version version;
      enum arm_smmu_implementation model;
+     const char * const *clks;
+     int num_clks;
 };

 #define ARM_SMMU_MATCH_DATA(name, ver, imp)  \
-static struct arm_smmu_match_data name = { .version = ver, .model = imp }
+static const struct arm_smmu_match_data name = { .version = ver, .model = imp }

 ARM_SMMU_MATCH_DATA(smmu_generic_v1, ARM_SMMU_V1, GENERIC_SMMU);
 ARM_SMMU_MATCH_DATA(smmu_generic_v2, ARM_SMMU_V2, GENERIC_SMMU);

@@ -1919,6 +1924,23 @@ static const struct of_device_id arm_smmu_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, arm_smmu_of_match);

+static void arm_smmu_fill_clk_data(struct arm_smmu_device *smmu,
+                                const char * const *clks)
+{
+     int i;
+
+     if (smmu->num_clks < 1)
+             return;
+
+     smmu->clks = devm_kcalloc(smmu->dev, smmu->num_clks,
+                               sizeof(*smmu->clks), GFP_KERNEL);
+     if (!smmu->clks)
+             return;
+
+     for (i = 0; i < smmu->num_clks; i++)
+             smmu->clks[i].id = clks[i];
+}
+
 #ifdef CONFIG_ACPI
 static int acpi_smmu_get_data(u32 model, struct arm_smmu_device *smmu)
 {

@@ -2001,6 +2023,9 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
      data = of_device_get_match_data(dev);
      smmu->version = data->version;
      smmu->model = data->model;
+     smmu->num_clks = data->num_clks;
+
+     arm_smmu_fill_clk_data(smmu, data->clks);

      parse_driver_options(smmu);

@@ -2099,6 +2124,14 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
              smmu->irqs[i] = irq;
      }

+     err = devm_clk_bulk_get(smmu->dev, smmu->num_clks, smmu->clks);
+     if (err)
+             return err;
+
+     err = clk_bulk_prepare(smmu->num_clks, smmu->clks);
+     if (err)
+             return err;
+
      err = arm_smmu_device_cfg_probe(smmu);
      if (err)
              return err;

@@ -2181,6 +2214,9 @@ static int arm_smmu_device_remove(struct platform_device *pdev)

      /* Turn the thing off */
      writel(sCR0_CLIENTPD, ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sCR0);
+
+     clk_bulk_unprepare(smmu->num_clks, smmu->clks);
+
      return 0;
 }

@@ -2197,7 +2233,27 @@ static int __maybe_unused arm_smmu_pm_resume(struct device *dev)
      return 0;
 }

-static SIMPLE_DEV_PM_OPS(arm_smmu_pm_ops, NULL, arm_smmu_pm_resume);
+static int __maybe_unused arm_smmu_runtime_resume(struct device *dev)
+{
+     struct arm_smmu_device *smmu = dev_get_drvdata(dev);
+
+     return clk_bulk_enable(smmu->num_clks, smmu->clks);
+}
+
+static int __maybe_unused arm_smmu_runtime_suspend(struct device *dev)
+{
+     struct arm_smmu_device *smmu = dev_get_drvdata(dev);
+
+     clk_bulk_disable(smmu->num_clks, smmu->clks);
+
+     return 0;
+}
+
+static const struct dev_pm_ops arm_smmu_pm_ops = {
+     SET_SYSTEM_SLEEP_PM_OPS(NULL, arm_smmu_pm_resume)

This is suspicious.

If you need a runtime suspend method, why do you think that it is not necessary
to suspend the device during system-wide transitions?

Okay, so you suggest to put clock disabling in say arm_smmu_pm_suspend()?
In that case the clocks have to be enabled in the resume path too.

I remember Tomasz pointed to that we shouldn't need clock enable in resume
path [1].

[1] https://lkml.org/lkml/2018/3/15/60


Best regards
Vivek

quoted

+     SET_RUNTIME_PM_OPS(arm_smmu_runtime_suspend,
+                        arm_smmu_runtime_resume, NULL)
+};

 static struct platform_driver arm_smmu_driver = {
      .driver = {

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