Re: [PATCH 2/3] dmaengine: rcar-dmac: Add missing dma_descriptor_unmap()

[Wolfram Sang <wsa+renesas@sang-engineering.com>]

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> > > This is easy to fix. If we can agree on switching unmapping before
> > > cookie completion, I can update this patch and then send a series to fix
> > > other drivers, too.
> > 
> > I agree with changing {cookie -> unmap}** to {unmap -> cookie} in this patch.
> > It looks like an improvement, I don't see any obvious downside to doing so.
> > 
> > Many drivers do {cookie -> unmap}, so it may be worth making the same change
> > there too. I haven't found a specific reason for that order in the history I
> > checked, but I'd also like to hear Frank's thoughts.
> 
> I cna chime in. I think Shashiko is correct here. We should ideally
> unmap first and then call complete. This would ensure anyone seeing the
> completion would get the right data buffer and chances of stale data are
> eliminated.
> 
> So Wolfram, can you please reverse the order.
> Also, lets document this.

Thanks for chiming in, Vinod. It seems we have consensus now, so I will
work on such a series next week. Thank you, everyone!


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