On Wed, Sep 07, 2016 at 01:47:22PM +0300, Felipe Balbi wrote: > > Hi, > > Robin Murphy <robin.murphy@xxxxxxx> writes: > > On 07/09/16 10:55, Peter Chen wrote: > > [...] > >>> Regarding the DMA configuration that you mention in ci_hdrc_add_device(), > >>> I think we should replace > >>> > >>> pdev->dev.dma_mask = dev->dma_mask; > >>> pdev->dev.dma_parms = dev->dma_parms; > >>> dma_set_coherent_mask(&pdev->dev, dev->coherent_dma_mask); > >>> > >>> with of_dma_configure(), which has the chance to configure more than > >>> just those three, as the dma API might look into different aspects: > >>> > >>> - iommu specific configuration > >>> - cache coherency information > >>> - bus type > >>> - dma offset > >>> - dma_map_ops pointer > >>> > >>> We try to handle everything in of_dma_configure() at configuration > >>> time, and that would be the place to add anything else that we might > >>> need in the future. > >>> > >> > >> Yes, I agree with you, but just like Felipe mentioned, we also need to > >> consider PCI device, can we do something like gpiod_get_index does? Are > >> there any similar APIs like of_dma_configure for ACPI? > > > > Not yet, but Lorenzo has one in progress[1], primarily for the sake of > > abstracting away the IOMMU configuration. > > > > Robin. > > > > [1]:http://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1209911.html > > not exported for drivers to use. If Lorenzo is trying to making a > matching API for ACPI systems, then it needs to follow what > of_dma_configure() is doing, and add an EXPORT_SYMBOL_GPL() That's easy enough, not sure I understand though why of_dma_deconfigure() is not exported then. The second question mark is about the dma-ranges equivalent in ACPI world; the _DMA method seems to be the exact equivalent but to the best of my knowledge it is ignored by the kernel, to really have an of_dma_configure() equivalent that's really necessary, unless we want to resort to arch specific methods (is that what x86 is currently doing ?) to retrieve/build the dma masks. Lorenzo -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
