linux-kernel - Re: [PATCH v2 04/12] i2c: riic: Use pm_runtime_resume_and

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Message-ID: <CAMuHMdV=Uhqar6k_z_wo5jzge_7oY4tBK5zNiBbpsWa39Wvabw@mail.gmail.com>
Date: Fri, 5 Jul 2024 09:19:46 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Andi Shyti <andi.shyti@...nel.org>
Cc: Claudiu <claudiu.beznea@...on.dev>, chris.brandt@...esas.com, robh@...nel.org, 
	krzk+dt@...nel.org, conor+dt@...nel.org, magnus.damm@...il.com, 
	mturquette@...libre.com, sboyd@...nel.org, p.zabel@...gutronix.de, 
	wsa+renesas@...g-engineering.com, linux-renesas-soc@...r.kernel.org, 
	linux-i2c@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org, 
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH v2 04/12] i2c: riic: Use pm_runtime_resume_and_get()

Hi Andi,

On Fri, Jul 5, 2024 at 12:42 AM Andi Shyti <andi.shyti@...nel.org> wrote:
> > diff --git a/drivers/i2c/busses/i2c-riic.c b/drivers/i2c/busses/i2c-riic.c
> > index 83e4d5e14ab6..002b11b020fa 100644
> > --- a/drivers/i2c/busses/i2c-riic.c
> > +++ b/drivers/i2c/busses/i2c-riic.c
> > @@ -113,6 +113,8 @@ struct riic_irq_desc {
> >       char *name;
> >  };
> >
> > +static const char * const riic_rpm_err_msg = "Failed to runtime resume";
>
> Please, don't do this. Much clearer to write the message
> explicitly.

And the compiler will merge all identical strings, emitting
just a single string.

>
> > +
> >  static inline void riic_writeb(struct riic_dev *riic, u8 val, u8 offset)
> >  {
> >       writeb(val, riic->base + riic->info->regs[offset]);
> > @@ -133,10 +135,14 @@ static int riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
> >       struct riic_dev *riic = i2c_get_adapdata(adap);
> >       struct device *dev = adap->dev.parent;
> >       unsigned long time_left;
> > -     int i;
> > +     int i, ret;
> >       u8 start_bit;
> >
> > -     pm_runtime_get_sync(dev);
> > +     ret = pm_runtime_resume_and_get(dev);
>
> In principle I like the error message to be always checked and I

s/message/condition/?

> will always approve it. Whenever there is a return value, even
> when we are sure it's always '0', it needs to be checked.
>
> I had lots of discussions in the past about this topic but I
> haven't always found support. I'd love to have the ack from a
> renesas maintainer here.

I don't mind checking for the error here.

>
> > +     if (ret) {
> > +             dev_err(dev, riic_rpm_err_msg);

Do you need to print these error messages?
AFAIU, this cannot happen anyway.
Ultimately, I expect the device driver that requested the transfer to
handle failures, and print a message when needed.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds