Messages in this thread | | | Date | Fri, 25 Mar 2022 23:40:42 +0530 | From | Manivannan Sadhasivam <> | Subject | Re: [PATCH 23/25] dmaengine: dw-edma: Bypass dma-ranges mapping for the local setup |
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On Thu, Mar 24, 2022 at 04:48:34AM +0300, Serge Semin wrote: > DW eDMA doesn't perform any translation of the traffic generated on the > CPU/Application side. It just generates read/write AXI-bus requests with > the specified addresses. But in case if the dma-ranges DT-property is > specified for a platform device node, Linux will use it to map the CPU > memory regions into the DMAable bus ranges. This isn't what we want for > the eDMA embedded into the locally accessed DW PCIe Root Port and > End-point. In order to work that around let's set the chan_dma_dev flag > for each DW eDMA channel thus forcing the client drivers to getting a > custom dma-ranges-less parental device for the mappings. > > Note it will only work for the client drivers using the > dmaengine_get_dma_device() method to get the parental DMA device. > > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru> > --- > drivers/dma/dw-edma/dw-edma-core.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c > index 72a51970bfba..ca5cd7c99571 100644 > --- a/drivers/dma/dw-edma/dw-edma-core.c > +++ b/drivers/dma/dw-edma/dw-edma-core.c > @@ -716,6 +716,21 @@ static int dw_edma_alloc_chan_resources(struct dma_chan *dchan) > if (chan->status != EDMA_ST_IDLE) > return -EBUSY; > > + /* Bypass the dma-ranges based memory regions mapping since the > + * inbound iATU only affects the traffic incoming from the > + * PCIe bus. > + */
Bypass the dma-ranges based memory regions mapping since eDMA doesn't do any address translation for the CPU address?
Other than this,
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Thanks, Mani
> + if (chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL) { > + dchan->dev->chan_dma_dev = true; > + > + dchan->dev->device.dma_coherent = chan->dw->chip->dev->dma_coherent; > + dma_coerce_mask_and_coherent(&dchan->dev->device, > + dma_get_mask(chan->dw->chip->dev)); > + dchan->dev->device.dma_parms = chan->dw->chip->dev->dma_parms; > + } else { > + dchan->dev->chan_dma_dev = false; > + } > + > pm_runtime_get(chan->dw->chip->dev); > > return 0; > -- > 2.35.1 >
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