[PATCH] dma: mv_xor_v2: new driver

[Thomas Petazzoni]

Hello,

On Wed, 15 Jun 2016 22:11:31 +0530, Vinod Koul wrote:

> > This is probably the only thing that I have not changed. The mv_xor
> > driver is already using the same strategy, and enqueuing in
> > issue_pending() would force us to add the request to a temporary linked
> > list, which would be dequeued in issue_pending(). This is quite a bit
> > of additional processing, while pushing the new requests directly to
> > the engine works fine.  
> 
> Well that is wrong! And patch is welcome for mv_xor as well :)
> 
> The DMAengine API mandates that we should submit a descriptor to a queue and
> then push them by invoking issue_pending.
> 
> The users are also expected to follow this

I have just sent a v4 that fixes this for the mv_xor_v2 driver. Now, in
->tx_submit() we only fill in the HW descriptors, but do not tell the
engine to process them. It's only at ->issue_pending() time that we
tell the engine that there N new descriptors to process.

I'll have a look at mv_xor a bit later.

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com