Hi, > I believe the reason for these api is because some arch changed to can > not do DMA on stack recently. Maybe we should have dma_mapping to bounce
It is not only arch dependent. You can enable virtual stacks in Kconfig, too. > buffer like it bounce un-dma-able address for those arch? or we should > have a common driver API for this, not just for i2c? I gave a talk about this problem recently and everyone in the room agreed the best thing would be to have annotated buffers which can be used kernel-wide. Someone mentioned DMABUF could be a candidate, but I haven't looked further into that. So, yes, a bigger solution is needed but I don't see that coming soon, so I implemented the I2C part for better safety now. I'd be happy to remove all that again once we have the annotated buffers. But it is an effort... Regards, Wolfram
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