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[v4,02/13] dt-bindings: document PASID property for IOMMU masters

Message ID 20191219163033.2608177-3-jean-philippe@linaro.org (mailing list archive)
State New, archived
Headers show
Series [v4,01/13] iommu/arm-smmu-v3: Drop __GFP_ZERO flag from DMA allocation | expand

Commit Message

Jean-Philippe Brucker Dec. 19, 2019, 4:30 p.m. UTC 
On Arm systems, some platform devices behind an SMMU may support the PASID
feature, which offers multiple address space. Let the firmware tell us
when a device supports PASID.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 Documentation/devicetree/bindings/iommu/iommu.txt | 6 ++++++
 1 file changed, 6 insertions(+)
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Patch

diff --git a/Documentation/devicetree/bindings/iommu/iommu.txt b/Documentation/devicetree/bindings/iommu/iommu.txt
index 5a8b4624defc..3c36334e4f94 100644
--- a/Documentation/devicetree/bindings/iommu/iommu.txt
+++ b/Documentation/devicetree/bindings/iommu/iommu.txt
@@ -86,6 +86,12 @@  have a means to turn off translation. But it is invalid in such cases to
 disable the IOMMU's device tree node in the first place because it would
 prevent any driver from properly setting up the translations.
 
+Optional properties:
+--------------------
+- pasid-num-bits: Some masters support multiple address spaces for DMA, by
+  tagging DMA transactions with an address space identifier. By default,
+  this is 0, which means that the device only has one address space.
+
 
 Notes:
 ======