On 07/13, Vivek Gautam wrote:

Hi Stephen,


On 07/13/2017 04:24 AM, Stephen Boyd wrote:

quoted

On 07/06, Vivek Gautam wrote:

quoted

@@ -1231,12 +1237,18 @@ static int arm_smmu_map(struct iommu_domain *domain, unsigned long iova,
 static size_t arm_smmu_unmap(struct iommu_domain *domain, unsigned long iova,
 			     size_t size)
 {
-	struct io_pgtable_ops *ops = to_smmu_domain(domain)->pgtbl_ops;
+	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
+	struct io_pgtable_ops *ops = smmu_domain->pgtbl_ops;
+	size_t ret;
 	if (!ops)
 		return 0;
-	return ops->unmap(ops, iova, size);
+	pm_runtime_get_sync(smmu_domain->smmu->dev);

Can these map/unmap ops be called from an atomic context? I seem
to recall that being a problem before.

That's something which was dropped in the following patch merged in master:
523d7423e21b iommu/arm-smmu: Remove io-pgtable spinlock

Looks like we don't  need locks here anymore?

While removing the spinlock around the map/unmap path may be one
thing, I'm not sure that's all of them. Is there a path from an
atomic DMA allocation (GFP_ATOMIC sort of thing) mapped into an
IOMMU for a device that can eventually get down to here and
attempt to turn a clk on?

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