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.Semin@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Alexey Malahov <Alexey.Malahov@xxxxxxxxxxxxxxxxxxxx> Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Rob Herring <robh+dt@xxxxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxxx Cc: devicetree@xxxxxxxxxxxxxxx --- 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
