Re: [PATCH 000/102] Convert drivers to explicit reset API

Philipp Zabel
2017-07-20T09:24:24Z

Hi Greg,

The patches in this series are completely independent of each other, and
I would like the subsystem maintainers to apply them at their own
leisure.
Well, except for the last one, which I will apply only after there are
no more users of the transition helpers.

On Thu, 2017-07-20 at 10:11 +0200, Greg Kroah-Hartman wrote:
> On Wed, Jul 19, 2017 at 05:25:04PM +0200, Philipp Zabel wrote:
> > The reset control API has two modes: exclusive access, where the driver
> > expects to have full and immediate control over the state of the reset
> > line, and shared (clock-like) access, where drivers only request reset
> > deassertion while active, but don't care about the state of the reset line
> > while inactive.
> >
> > Commit a53e35db70d1 ("reset: Ensure drivers are explicit when requesting
> > reset lines") started to transition the reset control request API calls
> > to explicitly state whether the driver needs exclusive or shared reset
> > control behavior.
> >
> > This series converts all drivers that currently implicitly request
> > exclusive reset controls to the corresponding explicit API call. It is,
> > for the most part, generated from the following semantic patch:
>
> Hey, I'm all for large api changes, but this really seems ackward, isn't
> there a "better" way to do this?

It is a bit awkward. I am sorry I haven't done this earlier. Quite a few
new drivers started using the old API after the explicit requests were
introduced last year.

> Why not, as you say the "implicit" request is exclusive, just leave
> everything alone and state that the "reset_control_get()" call is
> exclusive

I think it is better to let the drivers explicitly state what they
expect from the API, and using reset_control_get_exclusive vs _shared
helps driver developers to make a conscious decision.

Further, the implicit API call predates shared reset support, so it is
not clear that all of the old users really need exclusive control.
A few drivers have been switched to the shared API already.

> and make the shared one the "odd" usage as that seems to not
> be the normal case.

I am not sure, there have been people arguing that the "clock-like" case
really is the common one. I suppose some of those drivers touched by the
100 patches in this series could also be changed to shared. But I don't
dare to make this decision for each of them.

> That should be a much smaller patch right?
>
> That way you don't break everything here, and require 100+ patches to
> just change the name of a function from one to another and do nothing
> else.

I don't break anything here, and I'm absolutely fine with squashing
patches together per subsystem where that is preferable.

regards
Philipp