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authorLinus Torvalds <torvalds@linux-foundation.org>2022-08-06 10:56:45 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-08-06 10:56:45 -0700
commitc993e07be023acdeec8e84e2e0743c52adb5fc94 (patch)
tree873b039ee47b424a31829ffcda3c316c52bf78e4 /Documentation
parent1d239c1eb873c7d6c6cbc80d68330c939fd86136 (diff)
parent5c850d31880e00f063fa2a3746ba212c4bcc510f (diff)
Merge tag 'dma-mapping-5.20-2022-08-06' of git://git.infradead.org/users/hch/dma-mapping
Pull dma-mapping updates from Christoph Hellwig: - convert arm32 to the common dma-direct code (Arnd Bergmann, Robin Murphy, Christoph Hellwig) - restructure the PCIe peer to peer mapping support (Logan Gunthorpe) - allow the IOMMU code to communicate an optional DMA mapping length and use that in scsi and libata (John Garry) - split the global swiotlb lock (Tianyu Lan) - various fixes and cleanup (Chao Gao, Dan Carpenter, Dongli Zhang, Lukas Bulwahn, Robin Murphy) * tag 'dma-mapping-5.20-2022-08-06' of git://git.infradead.org/users/hch/dma-mapping: (45 commits) swiotlb: fix passing local variable to debugfs_create_ulong() dma-mapping: reformat comment to suppress htmldoc warning PCI/P2PDMA: Remove pci_p2pdma_[un]map_sg() RDMA/rw: drop pci_p2pdma_[un]map_sg() RDMA/core: introduce ib_dma_pci_p2p_dma_supported() nvme-pci: convert to using dma_map_sgtable() nvme-pci: check DMA ops when indicating support for PCI P2PDMA iommu/dma: support PCI P2PDMA pages in dma-iommu map_sg iommu: Explicitly skip bus address marked segments in __iommu_map_sg() dma-mapping: add flags to dma_map_ops to indicate PCI P2PDMA support dma-direct: support PCI P2PDMA pages in dma-direct map_sg dma-mapping: allow EREMOTEIO return code for P2PDMA transfers PCI/P2PDMA: Introduce helpers for dma_map_sg implementations PCI/P2PDMA: Attempt to set map_type if it has not been set lib/scatterlist: add flag for indicating P2PDMA segments in an SGL swiotlb: clean up some coding style and minor issues dma-mapping: update comment after dmabounce removal scsi: sd: Add a comment about limiting max_sectors to shost optimal limit ata: libata-scsi: cap ata_device->max_sectors according to shost->max_sectors scsi: scsi_transport_sas: cap shost opt_sectors according to DMA optimal limit ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt5
-rw-r--r--Documentation/core-api/dma-api.rst14
-rw-r--r--Documentation/x86/x86_64/boot-options.rst8
3 files changed, 23 insertions, 4 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 22d7b5127184..9dc68a12a5bf 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5999,8 +5999,11 @@
it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst)
swiotlb= [ARM,IA-64,PPC,MIPS,X86]
- Format: { <int> | force | noforce }
+ Format: { <int> [,<int>] | force | noforce }
<int> -- Number of I/O TLB slabs
+ <int> -- Second integer after comma. Number of swiotlb
+ areas with their own lock. Will be rounded up
+ to a power of 2.
force -- force using of bounce buffers even if they
wouldn't be automatically used by the kernel
noforce -- Never use bounce buffers (for debugging)
diff --git a/Documentation/core-api/dma-api.rst b/Documentation/core-api/dma-api.rst
index 6d6d0edd2d27..829f20a193ca 100644
--- a/Documentation/core-api/dma-api.rst
+++ b/Documentation/core-api/dma-api.rst
@@ -206,6 +206,20 @@ others should not be larger than the returned value.
::
+ size_t
+ dma_opt_mapping_size(struct device *dev);
+
+Returns the maximum optimal size of a mapping for the device.
+
+Mapping larger buffers may take much longer in certain scenarios. In
+addition, for high-rate short-lived streaming mappings, the upfront time
+spent on the mapping may account for an appreciable part of the total
+request lifetime. As such, if splitting larger requests incurs no
+significant performance penalty, then device drivers are advised to
+limit total DMA streaming mappings length to the returned value.
+
+::
+
bool
dma_need_sync(struct device *dev, dma_addr_t dma_addr);
diff --git a/Documentation/x86/x86_64/boot-options.rst b/Documentation/x86/x86_64/boot-options.rst
index 03ec9cf01181..cbd14124a667 100644
--- a/Documentation/x86/x86_64/boot-options.rst
+++ b/Documentation/x86/x86_64/boot-options.rst
@@ -287,11 +287,13 @@ iommu options only relevant to the AMD GART hardware IOMMU:
iommu options only relevant to the software bounce buffering (SWIOTLB) IOMMU
implementation:
- swiotlb=<pages>[,force]
- <pages>
- Prereserve that many 128K pages for the software IO bounce buffering.
+ swiotlb=<slots>[,force,noforce]
+ <slots>
+ Prereserve that many 2K slots for the software IO bounce buffering.
force
Force all IO through the software TLB.
+ noforce
+ Do not initialize the software TLB.
Miscellaneous