Hi, > -----Original Message----- > From: Conor Dooley <conor@xxxxxxxxxx> > Sent: Friday, September 22, 2023 3:34 PM > To: shravan Chippa - I35088 <Shravan.Chippa@xxxxxxxxxxxxx> > Cc: green.wan@xxxxxxxxxx; vkoul@xxxxxxxxxx; robh+dt@xxxxxxxxxx; > krzysztof.kozlowski+dt@xxxxxxxxxx; palmer@xxxxxxxxxxx; > paul.walmsley@xxxxxxxxxx; conor+dt@xxxxxxxxxx; palmer@xxxxxxxxxx; > dmaengine@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux- > riscv@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Nagasuresh Relli - > I67208 <Nagasuresh.Relli@xxxxxxxxxxxxx>; Praveen Kumar - I30718 > <Praveen.Kumar@xxxxxxxxxxxxx>; Conor Dooley - M52691 > <Conor.Dooley@xxxxxxxxxxxxx> > Subject: Re: [PATCH v1 3/3] dmaengine: sf-pdma: add mpfs-pdma compatible > name > > Hey Shravan, > > On Fri, Sep 22, 2023 at 03:20:39PM +0530, shravan chippa wrote: > > From: Shravan Chippa <shravan.chippa@xxxxxxxxxxxxx> > > > > Sifive platform dma does not allow out-of-order transfers, > > Can you remind me why we determined that this was the case? > IOW, why could we not enable the out-of-order transfers and get a > performance benefit for everyone? It's been a year or so (I think) and I have > forgotten. sf-dma is used for all Sifive RISC-V chipsets, but we will not be able to test on all of them in the microchip polar-fire FPGA SOC (RISC-V) platform we got good throughput with out-off-order transfers. so we thought of having a separate compatible name for sf-dma driver to use out-of-order transfers. Thanks, Shravan > > Cheers, > Conor. > > > buf out-of-order dma has a significant performance advantage. > > Add a PolarFire SoC specific compatible and code to support for > > out-of-order dma transfers > > > > Signed-off-by: Shravan Chippa <shravan.chippa@xxxxxxxxxxxxx> > > Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> > > Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> > > --- > > drivers/dma/sf-pdma/sf-pdma.c | 27 ++++++++++++++++++++++++--- > > drivers/dma/sf-pdma/sf-pdma.h | 6 ++++++ > > 2 files changed, 30 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/dma/sf-pdma/sf-pdma.c > > b/drivers/dma/sf-pdma/sf-pdma.c index c7558c9f9ac3..992a804166d5 > > 100644 > > --- a/drivers/dma/sf-pdma/sf-pdma.c > > +++ b/drivers/dma/sf-pdma/sf-pdma.c > > @@ -21,6 +21,7 @@ > > #include <linux/dma-mapping.h> > > #include <linux/of.h> > > #include <linux/of_dma.h> > > +#include <linux/of_device.h> > > #include <linux/slab.h> > > > > #include "sf-pdma.h" > > @@ -66,7 +67,7 @@ static struct sf_pdma_desc > > *sf_pdma_alloc_desc(struct sf_pdma_chan *chan) static void > sf_pdma_fill_desc(struct sf_pdma_desc *desc, > > u64 dst, u64 src, u64 size) > > { > > - desc->xfer_type = PDMA_FULL_SPEED; > > + desc->xfer_type = desc->chan->pdma->transfer_type; > > desc->xfer_size = size; > > desc->dst_addr = dst; > > desc->src_addr = src; > > @@ -520,6 +521,7 @@ static struct dma_chan *sf_pdma_of_xlate(struct > > of_phandle_args *dma_spec, > > > > static int sf_pdma_probe(struct platform_device *pdev) { > > + const struct sf_pdma_driver_platdata *ddata; > > struct sf_pdma *pdma; > > int ret, n_chans; > > const enum dma_slave_buswidth widths = @@ -545,6 +547,14 @@ > static > > int sf_pdma_probe(struct platform_device *pdev) > > > > pdma->n_chans = n_chans; > > > > + pdma->transfer_type = PDMA_FULL_SPEED; > > + > > + ddata = of_device_get_match_data(&pdev->dev); > > + if (ddata) { > > + if (ddata->quirks & NO_STRICT_ORDERING) > > + pdma->transfer_type &= ~(NO_STRICT_ORDERING); > > + } > > + > > pdma->membase = devm_platform_ioremap_resource(pdev, 0); > > if (IS_ERR(pdma->membase)) > > return PTR_ERR(pdma->membase); > > @@ -629,11 +639,22 @@ static int sf_pdma_remove(struct > platform_device *pdev) > > return 0; > > } > > > > +static const struct sf_pdma_driver_platdata mpfs_pdma = { > > + .quirks = NO_STRICT_ORDERING, > > +}; > > + > > static const struct of_device_id sf_pdma_dt_ids[] = { > > - { .compatible = "sifive,fu540-c000-pdma" }, > > - { .compatible = "sifive,pdma0" }, > > + { > > + .compatible = "sifive,fu540-c000-pdma", > > + }, { > > + .compatible = "sifive,pdma0", > > + }, { > > + .compatible = "microchip,mpfs-pdma", > > + .data = &mpfs_pdma, > > + }, > > {}, > > }; > > + > > MODULE_DEVICE_TABLE(of, sf_pdma_dt_ids); > > > > static struct platform_driver sf_pdma_driver = { diff --git > > a/drivers/dma/sf-pdma/sf-pdma.h b/drivers/dma/sf-pdma/sf-pdma.h > index > > 5c398a83b491..3b16db4daa0b 100644 > > --- a/drivers/dma/sf-pdma/sf-pdma.h > > +++ b/drivers/dma/sf-pdma/sf-pdma.h > > @@ -49,6 +49,7 @@ > > > > /* Transfer Type */ > > #define PDMA_FULL_SPEED 0xFF000008 > > +#define NO_STRICT_ORDERING BIT(3) > > > > /* Error Recovery */ > > #define MAX_RETRY 1 > > @@ -112,8 +113,13 @@ struct sf_pdma { > > struct dma_device dma_dev; > > void __iomem *membase; > > void __iomem *mappedbase; > > + u32 transfer_type; > > u32 n_chans; > > struct sf_pdma_chan chans[]; > > }; > > > > +struct sf_pdma_driver_platdata { > > + u32 quirks; > > +}; > > + > > #endif /* _SF_PDMA_H */ > > -- > > 2.34.1 > >