Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> writes: > Hi Robert, > >> * DMA_CTRL_ACK >> - - Undocumented feature >> - - No one really has an idea of what it's about, besides being >> - related to reusing the DMA transaction descriptors or having >> - additional transactions added to it in the async-tx API >> - - Useless in the case of the slave API >> + - if set, the TX transfer can be reused after being completed. > > Your sentences should start with an upper-case letter. Ack. >> + - there is a guarantee the TX won't be freed until it is acked >> + by async_tx_ack() > > We never talked about what a "TX transfer" is in the > documentation. That should be documented. I'll remove the "TX", the transfer is widely used in this documentation. > >> + - as a consequence, if a device driver wants to skip the dma_map_sg() and >> + dma_unmap_sg() because the DMA'd data wasn't used, it can resubmit the >> + transfer right after its completion. > > From a provider PoV, the data should always be mapped and / or > allocated in coherent way, so I'm not sure how does that's relevant in > the provider doc. It's relevant because it says the mapping/unmapping is not necessary _between_ 2 submission of a transfer. This implies it is mapped, as it is a requirement for the very first submission. > Also, we should still mention that it's !slave API only. Certainly not, it's fully slave API, that's the purpose of this patch. -- Robert -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
