On Wed, Sep 07, 2016 at 10:48:06AM +0200, Arnd Bergmann wrote: > On Wednesday, September 7, 2016 2:33:13 PM CEST Peter Chen wrote: > > > > > > Right, that should make it work with iommu as well. However, it does > > > not solve the other issue I mentioned above, with boards that have > > > USB devices hardwired to a chipidea host controller that need > > > configuration from DT. For that, we still need to come up with another > > > way to associate the DT hierarchy in the host bridge node with > > > the Linux platform_device. > > > > > > > Why? The DMA configuration is for host controller, not for USB device. > > No matter there is hardwired or hotplug devices, the DMA configuration > > for host controller are both inherited from glue layer platform devices, > > current implementation is at function ci_hdrc_add_device, > > drivers/usb/chipidea/core.c. > > I wasn't referring to DMA configuration there, but only to how we > set the of_node pointer in register_root_hub, which you added in > dc5878abf49 ("usb: core: move root hub's device node assignment after > it is added to bus") as: > > usb_dev->dev.of_node = parent_dev->of_node; > > As I understand, parent_dev (aka hcd->self.controller) here > refers to the device that you add in ci_hdrc_add_device(), > which does not have an of_node pointer, so we actually > want parent_dev->parent->of_node.
For platform devices, like chipidea and dwc3, it is correct, since they don't have of_node. If the host controller has of_node, it is controller's of_node. In order to let USB HCD core life be easy, we need to let hcd->self.controller own of_node when it is added to HCD core, no matter it has from the dts or get it dynamically. > > I'm sure you understand that code better than me, so let me > know what my mistake is if this indeed works correctly. > Your understanding is correct, just some have of_node from dts, some (chipidea/dwc3) need to have assignment at its driver. > > > 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? -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html