Hi Vivek, Thanks for the patch. Please see my comments inline.
On Wed, Feb 7, 2018 at 7:31 PM, Vivek Gautam <vivek.gau...@codeaurora.org> wrote: > From: Sricharan R <sricha...@codeaurora.org> > > The smmu device probe/remove and add/remove master device callbacks > gets called when the smmu is not linked to its master, that is without > the context of the master device. So calling runtime apis in those places > separately. > > Signed-off-by: Sricharan R <sricha...@codeaurora.org> > [vivek: Cleanup pm runtime calls] > Signed-off-by: Vivek Gautam <vivek.gau...@codeaurora.org> > --- > drivers/iommu/arm-smmu.c | 42 ++++++++++++++++++++++++++++++++++++++---- > 1 file changed, 38 insertions(+), 4 deletions(-) > > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > index 9e2f917e16c2..c024f69c1682 100644 > --- a/drivers/iommu/arm-smmu.c > +++ b/drivers/iommu/arm-smmu.c > @@ -913,11 +913,15 @@ static void arm_smmu_destroy_domain_context(struct > iommu_domain *domain) > struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain); > struct arm_smmu_device *smmu = smmu_domain->smmu; > struct arm_smmu_cfg *cfg = &smmu_domain->cfg; > - int irq; > + int ret, irq; > > if (!smmu || domain->type == IOMMU_DOMAIN_IDENTITY) > return; > > + ret = pm_runtime_get_sync(smmu->dev); > + if (ret) > + return; pm_runtime_get_sync() will return 0 if the device was powered off, 1 if it was already/still powered on or runtime PM is not compiled in, or a negative value on error, so shouldn't the test be (ret < 0)? Moreover, I'm actually wondering if it makes any sense to power up the hardware just to program it and power it down again. In a system where the IOMMU is located within a power domain, it would cause the IOMMU block to lose its state anyway. Actually, reflecting back on "[PATCH v7 2/6] iommu/arm-smmu: Add pm_runtime/sleep ops", perhaps it would make more sense to just control the clocks independently of runtime PM? Then, runtime PM could be used for real power management, e.g. really powering the block up and down, for further power saving. +Generally similar comments for other places in this patch. > + > /* > * Disable the context bank and free the page tables before freeing > * it. > @@ -932,6 +936,8 @@ static void arm_smmu_destroy_domain_context(struct > iommu_domain *domain) > > free_io_pgtable_ops(smmu_domain->pgtbl_ops); > __arm_smmu_free_bitmap(smmu->context_map, cfg->cbndx); > + > + pm_runtime_put_sync(smmu->dev); Is there any point in the put being sync here? [snip] > @@ -2131,6 +2152,14 @@ static int arm_smmu_device_probe(struct > platform_device *pdev) > if (err) > return err; > > + platform_set_drvdata(pdev, smmu); > + > + pm_runtime_enable(dev); I suspect this may be a disaster for systems where IOMMUs are located inside power domains, because the driver doesn't take care of the IOMMU block losing its state on physical power down, as I mentioned in my comments above. Best regards, Tomasz