Messages in this thread | | | From | Tomasz Figa <> | Date | Thu, 15 Mar 2018 15:18:08 +0900 | Subject | Re: [PATCH v9 4/5] iommu/arm-smmu: Add the device_link between masters and smmu |
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On Thu, Mar 15, 2018 at 2:50 AM, Robin Murphy <robin.murphy@arm.com> wrote: > On 13/03/18 08:55, Vivek Gautam wrote: >> >> From: Sricharan R <sricharan@codeaurora.org> >> >> 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@codeaurora.org> >> Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org> >> Reviewed-by: Tomasz Figa <tfiga@chromium.org> >> --- >> 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)) { > >> + 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?)
I think we care whether adding the link succeeded. If it fails to be added, we might end up with a complete system lockup on a system with power domains.
Best regards, Tomasz
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