Hi Tomasz,
On Tue, Feb 13, 2018 at 1:54 PM, Tomasz Figa <tf...@chromium.org> wrote: > 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)? Yes, I too noticed it while i was testing on a different platform, and was hitting a failure case. Will update at all places. > > 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? No, I don't think. Can manage with just a 'put' here. Will modify. best regards Vivek > > [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 -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
