Re: [PATCH] generic device DMA (dma_pool update)

Adam J. Richter (
Tue, 31 Dec 2002 15:38:51 -0800

Andrew Morton wrote:
>"Adam J. Richter" wrote:
>> David Brownell wrote:
>> >struct dma_pool *dma_pool_create(char *, struct device *, size_t)
>> >void dma_pool_destroy (struct dma_pool *pool)
>> >void *dma_pool_alloc(struct dma_pool *, int mem_flags, dma_addr_t *)
>> >void dma_pool_free(struct dma_pool *, void *, dma_addr_t)
>> I would like to be able to have failure-free, deadlock-free
>> blocking memory allocation, such as we have with the non-DMA mempool
>> library so that we can guarantee that drivers that have been
>> successfully initialized will continue to work regardless of memory
>> pressure, and reduce error branches that drivers have to deal with.
>> Such a facility could be layered on top of your interface
>> perhaps by extending the mempool code to pass an extra parameter
>> around. If so, then you should think about arranging your interface
>> so that it could be driven with as little glue as possible by mempool.

>What is that parameter? The size, I assume.

No, dma address. All allocations in a memory pool (in both
the mempool and pci_pool sense) are the same size.

Adam J. Richter __ ______________ 575 Oroville Road \ / Milpitas, California 95035
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