[PATCH 1/2] arm64: dma_mapping: allow PCI host driver to limit DMA mask

Arnd Bergmann
2017-02-16T16:12:55Z

On Thursday, December 29, 2016 11:45:03 PM CET Nikita Yushchenko wrote:
>
> static int __swiotlb_dma_supported(struct device *hwdev, u64 mask)
> {
> +#ifdef CONFIG_PCI
> + if (dev_is_pci(hwdev)) {
> + struct pci_dev *pdev = to_pci_dev(hwdev);
> + struct pci_host_bridge *br = pci_find_host_bridge(pdev->bus);
> +
> + if (br->dev.dma_mask && (*br->dev.dma_mask) &&
> + (mask & (*br->dev.dma_mask)) != mask)
> + return 0;
> + }
> +#endif
> if (swiotlb)
> return swiotlb_dma_supported(hwdev, mask);
> return 1;
>

I think it's wrong to make this a special case for PCI.

Instead, we should follow the dma-ranges properties during dma_set_mask()
to ensure we don't set a mask that any of the parents up to the root
cannot support.

Arnd