Maximum block size DW DMAC configuration corresponds to the max segment
size DMA parameter in the DMA core subsystem notation. Lets set it with a
value specific to the probed DW DMA controller. It shall help the DMA
clients to create size-optimized SG-list items for the controller. This in
turn will cause less dw_desc allocations, less LLP reinitializations,
better DMA device performance.
Signed-off-by: Serge Semin <sergey.se...@baikalelectronics.ru>
Cc: Alexey Malahov <alexey.mala...@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbog...@alpha.franken.de>
Cc: Arnd Bergmann <a...@arndb.de>
Cc: Rob Herring <robh...@kernel.org>
Cc: linux-m...@vger.kernel.org
Cc: devicet...@vger.kernel.org
---
Changelog v2:
- This is a new patch created in place of the dropped one:
"dmaengine: dw: Add LLP and block size config accessors".
Changelog v3:
- Use the block_size found for the very first channel instead of looking for
the maximum of maximum block sizes.
- Don't define device-specific device_dma_parameters object, since it has
already been defined by the platform device core.
---
drivers/dma/dw/core.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index 33e99d95b3d3..fb95920c429e 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -1229,6 +1229,13 @@ int do_dma_probe(struct dw_dma_chip *chip)
BIT(DMA_MEM_TO_MEM);
dw->dma.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+ /*
+ * For now there is no hardware with non uniform maximum block size
+ * across all of the device channels, so we set the maximum segment
+ * size as the block size found for the very first channel.
+ */
+ dma_set_max_seg_size(dw->dma.dev, dw->chan[0].block_size);
+
err = dma_async_device_register(&dw->dma);
if (err)
goto err_dma_register;
--
2.26.2
