Messages in this thread | | | From | Oliver Neukum <> | Subject | Re: PCI DMA to small buffers on cache-incoherent arch | Date | Wed, 12 Jun 2002 14:02:53 +0200 |
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> For your example, I don't buy it. You could well design the USB urb > allocation in such a way that they are passed down the controller of > a given device.
Urbs are not the problem. An urb abstractly speaking is just a description of io. It does not contain a buffer, just a pointer to it.
However many drivers allocate some of these buffers together with their device descriptors, which would, if a special allocator must be used, become impossible. Usbcore could allocate bounce buffers, but performance would suck.
If I understand both Davids correctly this is the solution. Buffers for dma must be allocated seperately using a special allocation function which is given the device so it can allocate correctly. David B wants a bus specific pointer to a function in the generic driver structure, right ?
Regards Oliver
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