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Diffstat (limited to 'Documentation/driver-api/dmaengine/provider.rst')
| -rw-r--r-- | Documentation/driver-api/dmaengine/provider.rst | 39 |
1 files changed, 35 insertions, 4 deletions
diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst index ddb0a81a796c..1594598b3317 100644 --- a/Documentation/driver-api/dmaengine/provider.rst +++ b/Documentation/driver-api/dmaengine/provider.rst @@ -162,6 +162,19 @@ Currently, the types available are: - The device is able to do memory to memory copies + - No matter what the overall size of the combined chunks for source and + destination is, only as many bytes as the smallest of the two will be + transmitted. That means the number and size of the scatter-gather buffers in + both lists need not be the same, and that the operation functionally is + equivalent to a ``strncpy`` where the ``count`` argument equals the smallest + total size of the two scatter-gather list buffers. + + - It's usually used for copying pixel data between host memory and + memory-mapped GPU device memory, such as found on modern PCI video graphics + cards. The most immediate example is the OpenGL API function + ``glReadPixels()``, which might require a verbatim copy of a huge + framebuffer from local device memory onto host memory. + - DMA_XOR - The device is able to perform XOR operations on memory areas @@ -183,6 +196,12 @@ Currently, the types available are: - The device is able to perform parity check using RAID6 P+Q algorithm against a memory buffer. +- DMA_MEMSET + + - The device is able to fill memory with the provided pattern + + - The pattern is treated as a single byte signed value. + - DMA_INTERRUPT - The device is able to trigger a dummy transfer that will @@ -198,10 +217,12 @@ Currently, the types available are: - DMA_ASYNC_TX - - Must not be set by the device, and will be set by the framework - if needed + - The device supports asynchronous memory-to-memory operations, + including memcpy, memset, xor, pq, xor_val, and pq_val. - - TODO: What is it about? + - This capability is automatically set by the DMA engine + framework and must not be configured manually by device + drivers. - DMA_SLAVE @@ -414,6 +435,12 @@ supported. - residue: Provides the residue bytes of the transfer for those that support residue. +- ``device_prep_peripheral_dma_vec`` + + - Similar to ``device_prep_slave_sg``, but it takes a pointer to a + array of ``dma_vec`` structures, which (in the long run) will replace + scatterlists. + - ``device_issue_pending`` - Takes the first transaction descriptor in the pending queue, @@ -434,7 +461,7 @@ supported. - Should use dma_set_residue to report it - In the case of a cyclic transfer, it should only take into - account the current period. + account the total size of the cyclic buffer. - Should return DMA_OUT_OF_ORDER if the device does not support in order completion and is completing the operation out of order. @@ -525,6 +552,10 @@ dma_cookie_t - Not really relevant any more since the introduction of ``virt-dma`` that abstracts it away. +dma_vec + +- A small structure that contains a DMA address and length. + DMA_CTRL_ACK - If clear, the descriptor cannot be reused by provider until the |