Messages in this thread | | | Subject | Re: [RFT][PATCH] generic device DMA implementation | Date | Sat, 28 Dec 2002 10:18:07 -0600 | From | James Bottomley <> |
| |
david-b@pacbell.net said: > The indirection is getting from the USB device (or interface) to the > object representing the USB controller. All USB calls need that, at > least for host-side APIs, since the controller driver is multiplexing > up to almost 4000 I/O channels. (127 devices * 31 endpoints, max; and > of course typical usage is more like dozens of channels.)
This sounds like a mirror of the problem of finding the IOMMU on parisc (there can be more than one).
The way parisc solves this is to look in dev->platform_data and if that's null walk up the dev->parent until the IOMMU is found and then cache the IOMMU ops in the current dev->platform_data. Obviously, you can't use platform_data, but you could use driver_data for this. The IOMMU's actually lie on a parisc specific bus, so the ability to walk up the device tree without having to know the device types was crucial to implementing this.
James
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |