Hello, > -----Original Message----- > From: Christoph Hellwig <h...@lst.de> > Sent: Monday, April 22, 2019 9:11 PM > > On Mon, Apr 22, 2019 at 07:51:25PM +0300, laurentiu.tu...@nxp.com wrote: > > From: Laurentiu Tudor <laurentiu.tu...@nxp.com> > > > > If possible / available call into the DMA API to get a proper iommu > > mapping and a dma address for the newly allocated coherent dma memory. > > I don't think this is so simple. The original use case of > dma_declare_coherent_memory was memory that is local to a device, where > we copy in data through a MMIO mapping and the device can then access > it. This use case still seems to be alive in the ohci-sm501 and > ohci-tmio drivers. Going through the iommu in those cases would be > counter productive.
I had a feeling that I didn't get the whole story and something isn't quite right with this patch. 😊 But I'm happy that we have a discussion started on the topic and, I must say, I'm very interested in getting to the bottom of it (I have some patches enabling SMMU on a couple of NXP chips and depend on resolving this). I'll try to understand what you're planning but in the meantime please let me know if you think I can be of any help. --- Thanks & Best Regards, Laurentiu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
