Re: [PATCH v2 08/13] dmaengine: at_xdmac: Move the free desc to the tail of the desc list

From: Vinod Koul
Date: Mon Dec 13 2021 - 04:00:08 EST


On 13-12-21, 08:51, Tudor.Ambarus@xxxxxxxxxxxxx wrote:
> Hi, Vinod,
>
> On 12/13/21 10:07 AM, Vinod Koul wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> >
> > On 25-11-21, 11:00, Tudor Ambarus wrote:
> >> So that we don't use the same desc over and over again.
> >
> > Please use full para in the changelog and not a continuation of the
> > patch title!
>
> Ok, will add a better commit description. Here and in other patches where
> your comment applies.

Great!

> >
> > and why is wrong with using same desc over and over? Any benefits of not
> > doing so?
>
> Not wrong, but if we move the free desc to the tail of the list, then the
> sequence of descriptors is more track-able in case of debug. You would
> know which descriptor should come next and you could easier catch
> concurrency over descriptors for example. I saw virt-dma uses
> list_splice_tail_init() as well, I found it a good idea, so I thought to
> follow the core driver.

Okay, I would be good to add this motivation in the change log. I am
sure after few you would also wonder why you did this change :)

--
~Vinod