linux-kernel - Re: [PATCH 2/2] PCI: mvebu: switch to using gpiod API

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Date:   Wed, 14 Sep 2022 14:10:21 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Kent Gibson <warthog618@...il.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Pali Rohár <pali@...nel.org>,
        Shawn Guo <shawn.guo@...aro.org>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] PCI: mvebu: switch to using gpiod API

On Wed, Sep 14, 2022 at 12:35 PM Linus Walleij <linus.walleij@...aro.org> wrote:
>
> On Wed, Sep 7, 2022 at 12:41 AM Dmitry Torokhov
> <dmitry.torokhov@...il.com> wrote:
>
> > Linus, do you think we should introduce GPIOD_OUT_INACTIVE /
> > GPIOD_OUT_ACTIVE or GPIOD_OUT_DEASSERTED / GPIOD_OUT_ASSERTED and
> > deprecate existing GPIOD_OUT_LOW and GPIO_OUT_HIGH?
>
> They should rather be replaced everywhere in one go.
>
> I think it is just a half-measure unless we also add
> #define GPIOD_ASSERTED 1
> #define GPIOD_DEASSERTED 0
> to be used instead of 1/0 in gpiod_set_value().
>

We've had that discussion for libgpiod and went with
GPIOD_VALUE_ACTIVE and GPIOD_VALUE_INACTIVE but...

> It would also imply changing the signature of the function
> gpiod_set_value() to gpiod_set_state() as we are not
> really setting a value but a state.
>

... now that you've mentioned it it does seem like
GPIOD_STATE_ACTIVE/INACTIVE makes much more sense as well as naming
the relevant functions gpiod_line_request_set_line_state() etc.

> I have thought about changing this, but the problem is that I felt
> it should be accompanied with a change fixing as many users
> as possible.
>
> I think this is one of those occasions where we should merge
> the new defines, and then send Linus Torvalds a sed script
> that he can run at the end of the merge window to change all
> gpiod_set_value(...., 1) -> gpiod_set_state(...., GPIOD_ASSERTED);
> everywhere.
>
> After all users are changed, the GPIOD_ASSERTED/DEASSERTED
> defined can be turned into an enum.
>
> That would be the silver bullet against a lot of confusion IMO.
>
> We would need Bartosz' input on this.
>

We can also let Linus know that we'll do it ourselves late in the
merge window and send a separate PR on Saturday before rc1?

Bart

> Yours,
> Linus Walleij