Hi,

On 21 October 2016 at 11:14, Sricharan R [off-list ref] wrote:

quoted

The smmu needs to be functional when the respective
master/s using it are active. As there is a device_link
between the master and smmu, the pm runtime ops for the smmu
gets invoked in sync with the master's runtime, thus the
smmu remains powered only when needed.

There are couple of places in the driver during probe,
master attach, where the smmu needs to be clocked without
the context of the master. So doing a pm_runtime_get/put sync
in those places separately.

Signed-off-by: Sricharan R <redacted>
---
 drivers/iommu/arm-smmu.c | 109 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 108 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 083489e4..45f2762 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c

@@ -45,6 +45,7 @@
 #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>

@@ -373,6 +374,8 @@ struct arm_smmu_device {
        u32                             num_global_irqs;
        u32                             num_context_irqs;
        unsigned int                    *irqs;
+       int                             num_clocks;
+       struct clk                      **clocks;

        u32                             cavium_id_base; /* Specific to Cavium */
 };

@@ -430,6 +433,31 @@ static struct arm_smmu_domain *to_smmu_domain(struct iommu_domain *dom)
        return container_of(dom, struct arm_smmu_domain, domain);
 }

+static int arm_smmu_enable_clocks(struct arm_smmu_device *smmu)
+{
+       int i, ret = 0;
+
+       for (i = 0; i < smmu->num_clocks; ++i) {
+               ret = clk_prepare_enable(smmu->clocks[i]);
+               if (ret) {
+                       dev_err(smmu->dev, "Couldn't enable clock #%d\n", i);
+                       while (i--)
+                               clk_disable_unprepare(smmu->clocks[i]);
+                       break;
+               }
+       }
+
+       return ret;
+}
+
+static void arm_smmu_disable_clocks(struct arm_smmu_device *smmu)
+{
+       int i;
+
+       for (i = 0; i < smmu->num_clocks; ++i)
+               clk_disable_unprepare(smmu->clocks[i]);
+}
+
 static void parse_driver_options(struct arm_smmu_device *smmu)
 {
        int i = 0;

@@ -1187,11 +1215,13 @@ static void arm_smmu_master_free_smes(struct iommu_fwspec *fwspec)
        int i, idx;

        mutex_lock(&smmu->stream_map_mutex);
+       pm_runtime_get_sync(smmu->dev);

Since this is generic code it is probably a good idea to check the
return value, same for _put_sync() below.

 Ok, i will do it for V2.

quoted

        for_each_cfg_sme(fwspec, i, idx) {
                if (arm_smmu_free_sme(smmu, idx))
                        arm_smmu_write_sme(smmu, idx);
                cfg->smendx[i] = INVALID_SMENDX;
        }
+       pm_runtime_put_sync(smmu->dev);
        mutex_unlock(&smmu->stream_map_mutex);
 }

@@ -1424,9 +1454,11 @@ static int arm_smmu_add_device(struct device *dev)
        while (i--)
                cfg->smendx[i] = INVALID_SMENDX;

+       pm_runtime_get_sync(smmu->dev);
        ret = arm_smmu_master_alloc_smes(dev);
        if (ret)
                goto out_free;
+       pm_runtime_put_sync(smmu->dev);

        return 0;

@@ -1650,6 +1682,44 @@ static int arm_smmu_id_size_to_bits(int size)
        }
 }

+static int arm_smmu_init_clocks(struct arm_smmu_device *smmu)
+{
+       const char *cname;
+       struct property *prop;
+       int i;
+       struct device *dev = smmu->dev;
+
+       smmu->num_clocks =
+               of_property_count_strings(dev->of_node, "clock-names");
+
+       if (smmu->num_clocks < 1)
+               return 0;
+
+       smmu->clocks = devm_kzalloc(dev,
+                                   sizeof(*smmu->clocks) * smmu->num_clocks,
+                                   GFP_KERNEL);
+
+       if (!smmu->clocks) {
+               dev_err(dev, "Failed to allocate memory for clocks\n");
+               return -ENODEV;
+       }
+
+       i = 0;

Please do the initialisation above when you declare the variable.

     ok, will change it.

Regards,
 Sricharan