Re: [PATCH] dma: mv_xor_v2: new driver

On Thu, Jun 16, 2016 at 02:42:24PM +0200, Thomas Petazzoni wrote:

Hello,

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

quoted

quoted

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.

Okay that sounds good to me, I will take a look at it..

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

Sounds fair enough

-- 
~Vinod
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