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| author | Alexandre Bounine <alexandre.bounine@idt.com> | 2014-08-08 14:22:12 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-08-08 15:57:24 -0700 |
| commit | 50835e977b69c3278bd5e4264737138346df133f (patch) | |
| tree | da891568dd1e4c7f9dae7e440d1ea2a6726aab93 /Documentation/rapidio | |
| parent | 4aff1ce7add1c432fe5ea3ae0231155f33e5ef38 (diff) | |
| download | lwn-50835e977b69c3278bd5e4264737138346df133f.tar.gz lwn-50835e977b69c3278bd5e4264737138346df133f.zip | |
rapidio/tsi721_dma: rework scatter-gather list handling
Rework Tsi721 RapidIO DMA engine support to allow handling data
scatter/gather lists longer than number of hardware buffer descriptors in
the DMA channel's descriptor list.
The current implementation of Tsi721 DMA transfers requires that number of
entries in a scatter/gather list provided by a caller of
dmaengine_prep_rio_sg() should not exceed number of allocated hardware
buffer descriptors.
This patch removes the limitation by processing long scatter/gather lists
by sections that can be transferred using hardware descriptor ring of
configured size. It also introduces a module parameter
"dma_desc_per_channel" to allow run-time configuration of Tsi721 hardware
buffer descriptor rings.
Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Andre van Herk <andre.van.herk@prodrive-technologies.com>
Cc: Stef van Os <stef.van.os@prodrive-technologies.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/rapidio')
| -rw-r--r-- | Documentation/rapidio/tsi721.txt | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/Documentation/rapidio/tsi721.txt b/Documentation/rapidio/tsi721.txt index 335f3c6087dc..626052f403bb 100644 --- a/Documentation/rapidio/tsi721.txt +++ b/Documentation/rapidio/tsi721.txt @@ -20,13 +20,26 @@ II. Known problems None. -III. To do +III. DMA Engine Support - Add DMA data transfers (non-messaging). - Add inbound region (SRIO-to-PCIe) mapping. +Tsi721 mport driver supports DMA data transfers between local system memory and +remote RapidIO devices. This functionality is implemented according to SLAVE +mode API defined by common Linux kernel DMA Engine framework. + +Depending on system requirements RapidIO DMA operations can be included/excluded +by setting CONFIG_RAPIDIO_DMA_ENGINE option. Tsi721 miniport driver uses seven +out of eight available BDMA channels to support DMA data transfers. +One BDMA channel is reserved for generation of maintenance read/write requests. + +If Tsi721 mport driver have been built with RAPIDIO_DMA_ENGINE support included, +this driver will accept DMA-specific module parameter: + "dma_desc_per_channel" - defines number of hardware buffer descriptors used by + each BDMA channel of Tsi721 (by default - 128). IV. Version History + 1.1.0 - DMA operations re-worked to support data scatter/gather lists larger + than hardware buffer descriptors ring. 1.0.0 - Initial driver release. V. License |