Messages in this thread | | | Date | Sun, 20 Jun 2004 16:59:51 -0400 | From | Jamey Hicks <> | Subject | Re: DMA API issues |
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James Bottomley wrote:
>On Fri, 2004-06-18 at 19:14, Ian Molton wrote: > > >>On 18 Jun 2004 19:04:11 -0500 >>James Bottomley <James.Bottomley@SteelEye.com> wrote: >> >> >> >>>Because the piece of memory you wish to access is bus remote. >>> >>> >>No, its *not* >> >>my CPU can write there directly. >> >>no strings attached. >> >>the DMA API just only understands how to map from RAM, not anything >>else. >> >> > >I think you'll actually find that it is. OHCI is a device (representing >a USB hub), it's attached to the system by some interface that >constitutes a bus (the bus interface transforming the CPU access cycles >to device access cycles, translating interrupts etc.). > > > Bus remote is a red herring in this case. The only difference between this case and the ones supported by the coherent_dma_mask is that the constraint on placement of the allocated memory cannot be encoded as a bitmask.
Jamey
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