On Fri, May 29, 2020 at 01:23:57AM +0300, Serge Semin wrote: > 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. Yes, something like that for time being, thanks! Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx> > 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 > -- With Best Regards, Andy Shevchenko
