On Fri, Jun 10, 2022 at 12:14:57PM +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@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> Thanks, Mani > > --- > > Changelog v2: > - Fix the comment a bit to being clearer. (@Manivannan) > > Changelog v3: > - Conditionally set dchan->dev->device.dma_coherent field since it can > be missing on some platforms. (@Manivannan) > - Remove Manivannan' rb and tb tags since the patch content has been > changed. > --- > drivers/dma/dw-edma/dw-edma-core.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c > index 6a8282eaebaf..4f56149dc8d8 100644 > --- a/drivers/dma/dw-edma/dw-edma-core.c > +++ b/drivers/dma/dw-edma/dw-edma-core.c > @@ -716,6 +716,26 @@ 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 for the eDMA > + * controlled from the CPU/Application side since in that case > + * the local memory address is left untranslated. > + */ > + if (chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL) { > + dchan->dev->chan_dma_dev = true; > + > +#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \ > + defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \ > + defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL) > + dchan->dev->device.dma_coherent = chan->dw->chip->dev->dma_coherent; > +#endif > + > + 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 > -- மணிவண்ணன் சதாசிவம்