Hi, I've read dma mapping and dma-api kernel documentation as well as the DMA API change at http://lwn.net/Articles/75780/ which describes fork of dma_sync_* to dma_sync_*_for_cpu and dma_sync_*_for_device. It seems the names of API are self explanatory and direction parameter is not needed (except for handling BIDIRECTIONAL case). So for e.g. If software wants to access the dma buffer, post DMA, it will invoke dma_sync_single_for_cpu so that non-coherent arch can invalidate the corresponding cache lines. This implies FROM_DEVICE semantics. Does that mean dma_sync_single_for_cpu invoked with direction = TO_DEVICE should return error. Corollary case is when dma_sync_single_for_device is invoked with direction = FROM_DEVICE, is tha error too (buggy driver). The architecture for which I'm implementing DMA coherency APIs has non-coherent DMA memory and logical-to-bus mapping / DMA bounce is not a issue. Thanks, Vineet -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
