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authorDavid S. Miller <davem@davemloft.net>2020-03-26 02:58:11 +0100
committerDavid S. Miller <davem@davemloft.net>2020-03-26 02:58:11 +0100
commit9fb16955fb661945ddffce4504dcffbe55cd518a (patch)
treee0811476a96a9411686e24f15a48d63cc6d02e49 /Documentation/driver-api/dmaengine/provider.rst
parentcxgb4: Add support to catch bits set in INT_CAUSE5 (diff)
parentMerge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net (diff)
downloadlinux-9fb16955fb661945ddffce4504dcffbe55cd518a.tar.xz
linux-9fb16955fb661945ddffce4504dcffbe55cd518a.zip
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Overlapping header include additions in macsec.c A bug fix in 'net' overlapping with the removal of 'version' string in ena_netdev.c Overlapping test additions in selftests Makefile Overlapping PCI ID table adjustments in iwlwifi driver. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/driver-api/dmaengine/provider.rst')
-rw-r--r--Documentation/driver-api/dmaengine/provider.rst12
1 files changed, 10 insertions, 2 deletions
diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst
index 790a15089f1f..56e5833e8a07 100644
--- a/Documentation/driver-api/dmaengine/provider.rst
+++ b/Documentation/driver-api/dmaengine/provider.rst
@@ -266,11 +266,15 @@ to use.
attached (via the dmaengine_desc_attach_metadata() helper to the descriptor.
From the DMA driver the following is expected for this mode:
+
- DMA_MEM_TO_DEV / DEV_MEM_TO_MEM
+
The data from the provided metadata buffer should be prepared for the DMA
controller to be sent alongside of the payload data. Either by copying to a
hardware descriptor, or highly coupled packet.
+
- DMA_DEV_TO_MEM
+
On transfer completion the DMA driver must copy the metadata to the client
provided metadata buffer before notifying the client about the completion.
After the transfer completion, DMA drivers must not touch the metadata
@@ -284,10 +288,14 @@ to use.
and dmaengine_desc_set_metadata_len() is provided as helper functions.
From the DMA driver the following is expected for this mode:
- - get_metadata_ptr
+
+ - get_metadata_ptr()
+
Should return a pointer for the metadata buffer, the maximum size of the
metadata buffer and the currently used / valid (if any) bytes in the buffer.
- - set_metadata_len
+
+ - set_metadata_len()
+
It is called by the clients after it have placed the metadata to the buffer
to let the DMA driver know the number of valid bytes provided.