Hi Robin,
On Wed, Mar 14, 2018 at 11:20 PM, Robin Murphy <robin.murphy@xxxxxxx> wrote:
> On 13/03/18 08:55, Vivek Gautam wrote:
>>
>> From: Sricharan R <sricharan@xxxxxxxxxxxxxx>
>>
>> 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.
>>
>> Signed-off-by: Sricharan R <sricharan@xxxxxxxxxxxxxx>
>> Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
>> Reviewed-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>
>> ---
>> drivers/iommu/arm-smmu.c | 29 +++++++++++++++++++++++++++++
>> 1 file changed, 29 insertions(+)
>>
>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
>> index 56a04ae80bf3..64953ff2281f 100644
>> --- a/drivers/iommu/arm-smmu.c
>> +++ b/drivers/iommu/arm-smmu.c
>> @@ -1460,10 +1460,31 @@ static int arm_smmu_add_device(struct device *dev)
>> iommu_device_link(&smmu->iommu, dev);
>> + if (pm_runtime_enabled(smmu->dev)) {
>> + struct device_link *link;
>> +
>> + /*
>> + * 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) {
>
>
> FWIW, given that we don't really care about link itself, I'd be quite happy
> to simplify that lot down to:
>
> if (pm_runtime_enabled(smmu_dev) &&
> !device_link_add(dev, smmu->dev, DL_FLAG_PM_RUNTIME)) {
Sure, will update this.
>
>> + dev_warn(smmu->dev,
>> + "Unable to add link to the consumer
>> %s\n",
>> + dev_name(dev));
>
>
> (side note: since device_link_add() already prints a message on success,
> maybe it could print its own failure message too?)
Should we make device_link that verbose - to print failure messages at
each step (there are atleast a couple where we return link as NULL),
or we can let the users handle printing the message?
regards
Vivek
>
> Robin.
>
>
>> + ret = -ENODEV;
>> + goto out_unlink;
>> + }
>> + }
>> +
>> arm_smmu_rpm_put(smmu);
>> return 0;
>> +out_unlink:
>> + iommu_device_unlink(&smmu->iommu, dev);
>> + arm_smmu_master_free_smes(fwspec);
>> out_rpm_put:
>> arm_smmu_rpm_put(smmu);
>> out_cfg_free:
>> @@ -1486,6 +1507,14 @@ static void arm_smmu_remove_device(struct device
>> *dev)
>> cfg = fwspec->iommu_priv;
>> smmu = cfg->smmu;
>> + if (pm_runtime_enabled(smmu->dev)) {
>> + struct device_link *link;
>> +
>> + link = device_link_find(dev, smmu->dev);
>> + if (link)
>> + device_link_del(link);
>> + }
>> +
>> ret = arm_smmu_rpm_get(smmu);
>> if (ret < 0)
>> return;
>>
>
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