Re: [RFC PATCH 3/8] mtd: rawnand: ams-delta: Set port direction once per transfer

Boris Brezillon
2018-07-20T19:29:29Z

On Fri, 20 Jul 2018 20:12:05 +0200
Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote:

> On Thursday, July 19, 2018 8:23:18 AM CEST Boris Brezillon wrote:
> > On Thu, 19 Jul 2018 01:57:05 +0200
> > Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote:
> >
> > > In its current shape, the driver sets data port direction before each
> > > byte read/write operation, even during multi-byte transfers. Optimize
> > > that by setting the port direction only on first byte of each transfer.
> >
> > Sounds like premature optimization for something you'll rework when
> > fully switching to the GPIO consumer API to control the DATA bus.
>
> Indeed, this optimization was crucial for getting acceptable performance of
> data transfers over GPIO. I'm only not sure if there is any action in
> response to your comment expected on my side, e.g., did you want to say I
> should modify the patch description, or change the order of patches?

I'm just saying that, since you switch to a solution that goes through
the GPIO framework to control the data bus, making sure the the pin
direction change is done only once when reading/writing several bytes is
something you can do after/when transitioning to the new approach.

So yes, I suggest to re-order patches, except that this patch won't
look the same at all if you move it after the "use the GPIO consumer
API to control data bus" patch.