On Fri, Dec 07, 2018 at 04:31:35PM +0000, Robin Murphy wrote:
> Rather than checking the DMA attribute at each callsite, just pass it
> through for acpi_dma_configure() to handle directly. That can then deal
> with the relatively exceptional DEV_DMA_NOT_SUPPORTED case by explicitly
> installing dummy DMA ops instead of just skipping setup entirely. This
> will then free up the dev->dma_ops == NULL case for some valuable
> fastpath optimisations.
>
> CC: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
> CC: Len Brown <lenb@xxxxxxxxxx>
> CC: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> CC: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
FWIW, if this hasn't been applied already (I think you targeted a DMA
tree):
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> ---
> drivers/acpi/scan.c | 5 +++++
> drivers/base/platform.c | 3 +--
> drivers/pci/pci-driver.c | 3 +--
> 3 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index bd1c59fb0e17..b75ae34ed188 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -1456,6 +1456,11 @@ int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr)
> const struct iommu_ops *iommu;
> u64 dma_addr = 0, size = 0;
>
> + if (attr == DEV_DMA_NOT_SUPPORTED) {
> + set_dma_ops(dev, &dma_dummy_ops);
> + return 0;
> + }
> +
> iort_dma_setup(dev, &dma_addr, &size);
>
> iommu = iort_iommu_configure(dev);
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 41b91af95afb..c6daca875c17 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -1138,8 +1138,7 @@ int platform_dma_configure(struct device *dev)
> ret = of_dma_configure(dev, dev->of_node, true);
> } else if (has_acpi_companion(dev)) {
> attr = acpi_get_dma_attr(to_acpi_device_node(dev->fwnode));
> - if (attr != DEV_DMA_NOT_SUPPORTED)
> - ret = acpi_dma_configure(dev, attr);
> + ret = acpi_dma_configure(dev, attr);
> }
>
> return ret;
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index bef17c3fca67..f899a28b90f8 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -1602,8 +1602,7 @@ static int pci_dma_configure(struct device *dev)
> struct acpi_device *adev = to_acpi_device_node(bridge->fwnode);
> enum dev_dma_attr attr = acpi_get_dma_attr(adev);
>
> - if (attr != DEV_DMA_NOT_SUPPORTED)
> - ret = acpi_dma_configure(dev, attr);
> + ret = acpi_dma_configure(dev, attr);
> }
>
> pci_put_host_bridge_device(bridge);
> --
> 2.19.1.dirty
>
>
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