Messages in this thread |  | | From | "Manfred Spraul" <> | Subject | Re: how to get virtual address from dma address | Date | Wed, 3 Oct 2001 23:30:57 +0200 |
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> Then why isn't there a call like pci_unmap_single()
<<< linux/include/asm-i386/pci.h: /* Unmap a single streaming mode DMA translation. The dma_addr and size * must match what was provided for in a previous pci_map_single call. All * other usages are undefined. * * After this call, reads by the cpu to the buffer are guarenteed to see * whatever the device wrote there. */ static inline void pci_unmap_single(struct pci_dev *hwdev, dma_addr_t dma_addr, size_t size, int direction) <<<<
Please try to store both the dma address and the virtual address in your driver and use pci_map_single(). I'm aware of one case where that's not possible: if your hardware builds a linked list of finished commands, and that list is in DMA addresses, not virtual addresses. I think both sym53c8xx and one of the USB controllers (usb-ohci.c?) have that problem, they use a hash table for the reverse dma address->linear address mapping.
I hope that answers your question.
-- Manfred
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