Messages in this thread | | | Date | Wed, 31 Aug 2022 09:36:46 +0100 | Subject | Re: [PATCH v5 20/20] PCI: dwc: Add Baikal-T1 PCIe controller support | From | Robin Murphy <> |
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On 2022-08-29 16:28, Lorenzo Pieralisi wrote: [...] >> +static int bt1_pcie_add_port(struct bt1_pcie *btpci) >> +{ >> + struct device *dev = &btpci->pdev->dev; >> + int ret; >> + >> + /* >> + * DW PCIe Root Port controller is equipped with eDMA capable of >> + * working with the 64-bit memory addresses. >> + */ >> + ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64)); >> + if (ret) >> + return ret; > > Is this the right place to set the DMA mask for the host controller > embedded DMA controller (actually, the dev pointer is the _host_ > controller device) ? > > How this is going to play when combined with: > > https://lore.kernel.org/linux-pci/1e63a581-14ae-b4b5-a5bf-ca8f09c33af6@arm.com > > It is getting a bit confusing. I believe the code in the link > above sets the mask so that through the DMA API we are capable > of getting an MSI doorbell virtual address whose physical address > can be addressed by the endpoint; this through the DMA API. > > This patch is setting the DMA mask for a different reason, namely > setting the host controller embedded DMA controller addressing > capabilities. > > AFAICS - both approaches set the mask for the same device - now > the question is about which one is legitimate and how to handle > the other.
Assuming the dw-edma-pcie driver is the relevant one, that already sets its own masks on its own device, so I also don't see why this is here.
Thanks, Robin.
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