Hi, Changes since v1: - Move code from header to dmaengine.c - Fix spelling - Use BIT() macro for bit definition - Update both provider and client documentation Changes since rfc: - DESC_METADATA_EMBEDDED renamed to DESC_METADATA_ENGINE - Use flow is added for both CLIENT and ENGINE metadata modes Some data movement architecure (DMA controller and peripherals) uses metadata associated with a transaction. The DMA controller role is to transfer the payload and the metadata alongside. The metadata itself is not used by the DMA engine itself, but it contains parameters, keys, vectors, etc for peripheral or from the peripheral. The DMAengine framework provides a generic ways to facilitate the metadata for descriptors. Depending on the architecture the DMA driver can implment either or both of the methods and it is up to the client driver to choose which one to use. If the DMA supports per descriptor metadata it can implement the attach, get_ptr/set_len callbacks. Client drivers must only use either attach or get_ptr/set_len to avoid miss configuration. Client driver can check if a given metadata mode is supported by the channel during probe time with dmaengine_is_metadata_mode_supported(chan, DESC_METADATA_CLIENT); dmaengine_is_metadata_mode_supported(chan, DESC_METADATA_ENGINE); and based on this information can use either mode. Wrappers are also added for the metadata_ops. To be used in DESC_METADATA_CLIENT mode: dmaengine_desc_attach_metadata() To be used in DESC_METADATA_ENGINE mode: dmaengine_desc_get_metadata_ptr() dmaengine_desc_set_metadata_len() Regards, Peter --- Peter Ujfalusi (2): dmaengine: Add metadata_ops for dma_async_tx_descriptor dmaengine: doc: Add sections for per descriptor metadata support Documentation/driver-api/dmaengine/client.rst | 70 ++++++++++++ .../driver-api/dmaengine/provider.rst | 46 ++++++++ drivers/dma/dmaengine.c | 73 ++++++++++++ include/linux/dmaengine.h | 108 ++++++++++++++++++ 4 files changed, 297 insertions(+) -- Peter Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
