Messages in this thread | | | Date | Wed, 06 May 2015 11:08:52 +0100 | From | Robin Murphy <> | Subject | Re: [V2 PATCH 2/5] arm64 : Introduce support for ACPI _CCA object |
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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.
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