Messages in this thread | | | From | "Nikita V. Youshchenko" <> | Subject | high-order allocation + highmem + streaming DMA - possible? | Date | Wed, 19 Oct 2011 10:45:40 +0400 |
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Hello.
We are writing a driver for a custom PCI device that receives large amount of data.
Device is capable of DMAing received data in 64k chunks.
We have been going to: - use physically-continuous 64k-sized memory areas using alloc_pages() with order=4, - allocate large number of such areas on driver init, - implement mmap() to map those all to userspace for zero-copy processing, - use streaming DMA to actually receive data
However I can't find a way to use streaming DMA for large highmem areas. - pci_map_single() is for linear mapping and can't work with highmem - pci_map_page() can work with highmem but is limited to one page - pci_map_sg() is for s/g lists, not for single 64k blocks.
Is there a way to use streaming DMA with large memory areas located in highmem? Or in this situation buffers in highmem can't be used?
Nikita
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