linux-kernel - Re: [PATCH] mbox: qcom: avoid unused-variable warning

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Date:   Thu, 26 Sep 2019 15:07:13 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Andy Gross <agross@...nel.org>,
        Jassi Brar <jassisinghbrar@...il.com>,
        Niklas Cassel <niklas.cassel@...aro.org>,
        Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Jassi Brar <jaswinder.singh@...aro.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mbox: qcom: avoid unused-variable warning

Hi Stephen,

On Fri, Sep 20, 2019 at 11:06 PM Stephen Boyd <sboyd@...nel.org> wrote:
> Quoting Arnd Bergmann (2019-09-20 12:27:50)
> > On Fri, Sep 20, 2019 at 6:45 PM Stephen Boyd <sboyd@...nel.org> wrote:
> > > > @@ -54,11 +60,6 @@ static int qcom_apcs_ipc_probe(struct platform_device *pdev)
> > > >         void __iomem *base;
> > > >         unsigned long i;
> > > >         int ret;
> > > > -       const struct of_device_id apcs_clk_match_table[] = {
> > >
> > > Does marking it static here work too? It would be nice to limit the
> > > scope of this variable to this function instead of making it a global.
> > > Also, it might be slightly smaller code size if that works.
> >
> > No, I just tried and the warning returned.

It's there for the convenience for the user, so he doesn't have to add it
himself explicitly.

> ("of/device: Nullify match table in of_match_device() for CONFIG_OF=n"),
> but it's been 5 years! Surely we can revert this change now that commit
> 219a7bc577e6 ("spi: rspi: Use of_device_get_match_data() helper") is
> merged.

Right, the particular error case in the RSPI driver can no longer happen.

Calling of_device_get_match_data() is the better solution anyway, as
that uses the match table stored in dev->driver->of_match_table, so
there's no need to pass the table explicitly, and conditionally.

Hence...

> --- a/drivers/leds/leds-pca9532.c
> +++ b/drivers/leds/leds-pca9532.c
> @@ -472,7 +472,7 @@ pca9532_of_populate_pdata(struct device *dev, struct device_node *np)
>         int i = 0;
>         const char *state;
>
> -       match = of_match_device(of_pca9532_leds_match, dev);
> +       match = of_match_device(of_match_ptr(of_pca9532_leds_match), dev);
>         if (!match)
>                 return ERR_PTR(-ENODEV);

Please convert to of_device_get_match_data() instead of adding
of_match_ptr() invocations...

> @@ -525,7 +525,7 @@ static int pca9532_probe(struct i2c_client *client,
>                         dev_err(&client->dev, "no platform data\n");
>                         return -EINVAL;
>                 }
> -               of_id = of_match_device(of_pca9532_leds_match,
> +               of_id = of_match_device(of_match_ptr(of_pca9532_leds_match),

Likewise.

> --- a/sound/soc/jz4740/jz4740-i2s.c
> +++ b/sound/soc/jz4740/jz4740-i2s.c
> @@ -503,7 +503,7 @@ static int jz4740_i2s_dev_probe(struct platform_device *pdev)
>         if (!i2s)
>                 return -ENOMEM;
>
> -       match = of_match_device(jz4740_of_matches, &pdev->dev);
> +       match = of_match_device(of_match_ptr(jz4740_of_matches), &pdev->dev);

Given of_device_get_match_data() returns NULL, not an error code, even
this one could use of_device_get_match_data().

>         if (match)
>                 i2s->version = (enum jz47xx_i2s_version)match->data;

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