On Mon, Dec 12, 2022 at 01:51:37PM -0800, Georgi Djakov wrote: > Document the "iova-best-fit" device-tree property, which is used to > describe that the iommu master is constrained on memory and the system > must put more effort when allocating IOVAs to avoid holes/gaps in > memory. This improves the memory utilization and helps with memory > fragmentation issues in some cases, but it could take longer to allocate > an IOVA compared with the default "first-fit" algorithm. > > Signed-off-by: Georgi Djakov <quic_c_gdjako@xxxxxxxxxxx> > --- > Documentation/devicetree/bindings/iommu/iommu.txt | 4 ++++ > 1 file changed, 4 insertions(+) No new properties in common .txt files. Schemas only. However, this looks like kernel policy which doesn't belong in DT. > diff --git a/Documentation/devicetree/bindings/iommu/iommu.txt b/Documentation/devicetree/bindings/iommu/iommu.txt > index 26ba9e530f13..ca1b4813c5bf 100644 > --- a/Documentation/devicetree/bindings/iommu/iommu.txt > +++ b/Documentation/devicetree/bindings/iommu/iommu.txt > @@ -88,6 +88,10 @@ prevent any driver from properly setting up the translations. > > Optional properties: > -------------------- > +- iova-best-fit: When present, the best-fit algorithm will be used, instead > + of first-fit. This reduces memory fragmentation when allocating IOVAs in > + some cases, but may also increase the time it takes to allocate an IOVA. > + > - 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. >
