Hi Robin/Vivek,

On 2/1/2018 2:23 PM, Vivek Gautam wrote:

Hi,


On 1/31/2018 6:39 PM, Robin Murphy wrote:

quoted

On 19/01/18 11:43, Vivek Gautam wrote:

quoted

From: Sricharan R <redacted>

Finally add the device link between the master device and
smmu, so that the smmu gets runtime enabled/disabled only when the
master needs it. This is done from add_device callback which gets
called once when the master is added to the smmu.

Don't we need to balance this with a device_link_del() in .remove_device (like exynos-iommu does)?

Right. Will add device_link_del() call. Thanks for pointing out.

 The reason for not adding device_link_del from .remove_device was, the core device_del 
 which calls the .remove_device from notifier, calls device_links_purge before that.
 That does the same thing as device_link_del. So by the time .remove_device is called,
 device_links for that device is already cleaned up. Vivek, you may want to check once that
 calling device_link_del from .remove_device has no effect, just to confirm once more.

Regards,
 Sricharan
 

regards
Vivek

quoted

Robin.

quoted

Signed-off-by: Sricharan R <redacted>
---
  drivers/iommu/arm-smmu.c | 11 +++++++++++
  1 file changed, 11 insertions(+)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 95478bfb182c..33bbcfedb896 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c

@@ -1367,6 +1367,7 @@ static int arm_smmu_add_device(struct device *dev)

      struct arm_smmu_device *smmu;
      struct arm_smmu_master_cfg *cfg;
      struct iommu_fwspec *fwspec = dev->iommu_fwspec;
+    struct device_link *link;
      int i, ret;
        if (using_legacy_binding) {

@@ -1428,6 +1429,16 @@ static int arm_smmu_add_device(struct device *dev)

        pm_runtime_put_sync(smmu->dev);
  +    /*
+     * Establish the link between smmu and master, so that the
+     * smmu gets runtime enabled/disabled as per the master's
+     * needs.
+     */
+    link = device_link_add(dev, smmu->dev, DL_FLAG_PM_RUNTIME);
+    if (!link)
+        dev_warn(smmu->dev, "Unable to create device link between %s and %s\n",
+             dev_name(smmu->dev), dev_name(dev));
+
      return 0;
    out_cfg_free:

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