Hi Suravee,
On 05/05/15 16:12, Suravee Suthikulpanit wrote:
From http://www.uefi.org/sites/default/files/resources/ACPI_6.0.pdf, section 6.2.17 _CCA states that ARM platforms require ACPI _CCA object to be specified for DMA-cabpable devices. This patch introduces ACPI_MUST_HAVE_CCA in arm64 Kconfig to specify such requirement.
In this case of missing _CCA, arm64 would assign dummy_dma_ops to disable DMA capability of the device.
Signed-off-by: Mark Salter msalter@redhat.com Signed-off-by: Suravee Suthikulpanit Suravee.Suthikulpanit@amd.com
[...]
+static void __dummy_sync_single_for_cpu(struct device *dev,
dma_addr_t dev_addr, size_t size,enum dma_data_direction dir)+{ +}
+static void __dummy_sync_single_for_device(struct device *dev,
dma_addr_t dev_addr, size_t size,enum dma_data_direction dir)+{ +}
Minor point, but I don't see the need to have multiple dummy functions with identical signatures - just have a generic dummy_sync_single and assign it to both ops.
+static void __dummy_sync_sg_for_cpu(struct device *dev,
struct scatterlist *sgl, int nelems,enum dma_data_direction dir)+{ +}
+static void __dummy_sync_sg_for_device(struct device *dev,
struct scatterlist *sgl, int nelems,enum dma_data_direction dir)+{ +}
Ditto here with dummy_sync_sg.
I wonder if there's any argument for putting the dummy DMA ops somewhere common, like drivers/base/dma-mapping.c?
Robin.