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@xxxxxxxxxx>
Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>
---
[...]
+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.
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