Hi Robert, On Thu, May 14, 2015 at 07:53:26PM +0200, Robert Jarzmik wrote: > Add documentation about acking the transfers, and their > reusability. > > Signed-off-by: Robert Jarzmik <robert.jarzmik@xxxxxxx> > --- > Documentation/dmaengine/provider.txt | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/Documentation/dmaengine/provider.txt b/Documentation/dmaengine/provider.txt > index 05d2280..33a81ce 100644 > --- a/Documentation/dmaengine/provider.txt > +++ b/Documentation/dmaengine/provider.txt > @@ -345,11 +345,12 @@ where to put them) > that abstracts it away. > > * 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. > + - 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. > + - 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. Also, we should still mention that it's !slave API only. Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com
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