mbox: qcom: avoid unused-variable warning

Message ID 20190920145543.1732316-1-arnd@arndb.de
State New
Headers show
Series
  • mbox: qcom: avoid unused-variable warning
Related show

Commit Message

Arnd Bergmann Sept. 20, 2019, 2:55 p.m.
Without CONFIG_OF, there is no reference to the apcs_clk_match_table[]
array, causing a harmless warning:

drivers/mailbox/qcom-apcs-ipc-mailbox.c:57:28: error: unused variable 'apcs_clk_match_table' [-Werror,-Wunused-variable]
        const struct of_device_id apcs_clk_match_table[] = {

Move the variable out of the variable scope and mark it 'static'
to avoid the warning (static const variables get silently dropped
by the compiler), and avoid the on-stack copy at the same time.

Fixes: 78c86458a440 ("mbox: qcom: add APCS child device for QCS404")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 drivers/mailbox/qcom-apcs-ipc-mailbox.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

-- 
2.20.0

Comments

Stephen Boyd Sept. 20, 2019, 4:45 p.m. | #1
Quoting Arnd Bergmann (2019-09-20 07:55:29)
> Without CONFIG_OF, there is no reference to the apcs_clk_match_table[]

> array, causing a harmless warning:

> 

> drivers/mailbox/qcom-apcs-ipc-mailbox.c:57:28: error: unused variable 'apcs_clk_match_table' [-Werror,-Wunused-variable]

>         const struct of_device_id apcs_clk_match_table[] = {

> 

> Move the variable out of the variable scope and mark it 'static'

> to avoid the warning (static const variables get silently dropped

> by the compiler), and avoid the on-stack copy at the same time.

> 

> Fixes: 78c86458a440 ("mbox: qcom: add APCS child device for QCS404")

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> ---

>  drivers/mailbox/qcom-apcs-ipc-mailbox.c | 11 ++++++-----

>  1 file changed, 6 insertions(+), 5 deletions(-)

> 

> diff --git a/drivers/mailbox/qcom-apcs-ipc-mailbox.c b/drivers/mailbox/qcom-apcs-ipc-mailbox.c

> index eeebafd546e5..10557a950c2d 100644

> --- a/drivers/mailbox/qcom-apcs-ipc-mailbox.c

> +++ b/drivers/mailbox/qcom-apcs-ipc-mailbox.c

> @@ -45,6 +45,12 @@ static const struct mbox_chan_ops qcom_apcs_ipc_ops = {

>         .send_data = qcom_apcs_ipc_send_data,

>  };

>  

> +static const struct of_device_id apcs_clk_match_table[] = {

> +       { .compatible = "qcom,msm8916-apcs-kpss-global", },

> +       { .compatible = "qcom,qcs404-apcs-apps-global", },

> +       {}

> +};

> +

>  static int qcom_apcs_ipc_probe(struct platform_device *pdev)

>  {

>         struct qcom_apcs_ipc *apcs;

> @@ -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.

> -               { .compatible = "qcom,msm8916-apcs-kpss-global", },

> -               { .compatible = "qcom,qcs404-apcs-apps-global", },

> -               {}

> -       };

>  

>         apcs = devm_kzalloc(&pdev->dev, sizeof(*apcs), GFP_KERNEL);

>         if (!apcs)
Arnd Bergmann Sept. 20, 2019, 7:27 p.m. | #2
On Fri, Sep 20, 2019 at 6:45 PM Stephen Boyd <sboyd@kernel.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.

      Arnd
Geert Uytterhoeven Sept. 26, 2019, 1:07 p.m. | #3
Hi Stephen,

On Fri, Sep 20, 2019 at 11:06 PM Stephen Boyd <sboyd@kernel.org> wrote:
> Quoting Arnd Bergmann (2019-09-20 12:27:50)

> > On Fri, Sep 20, 2019 at 6:45 PM Stephen Boyd <sboyd@kernel.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@linux-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
Stephen Boyd Sept. 27, 2019, 6:26 p.m. | #4
Quoting Geert Uytterhoeven (2019-09-26 06:07:13)
> Hi Stephen,

> 

> On Fri, Sep 20, 2019 at 11:06 PM Stephen Boyd <sboyd@kernel.org> wrote:

> > Quoting Arnd Bergmann (2019-09-20 12:27:50)

> > > On Fri, Sep 20, 2019 at 6:45 PM Stephen Boyd <sboyd@kernel.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...


How is this workable? I left it as of_match_device() because the value
returned may be 0 for the enum and that looks the same as NULL.

> 

> > @@ -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().

>
Geert Uytterhoeven Sept. 27, 2019, 7:10 p.m. | #5
Hi Stephen,

On Fri, Sep 27, 2019 at 8:26 PM Stephen Boyd <sboyd@kernel.org> wrote:
> Quoting Geert Uytterhoeven (2019-09-26 06:07:13)

> > On Fri, Sep 20, 2019 at 11:06 PM Stephen Boyd <sboyd@kernel.org> wrote:

> > > Quoting Arnd Bergmann (2019-09-20 12:27:50)

> > > > On Fri, Sep 20, 2019 at 6:45 PM Stephen Boyd <sboyd@kernel.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...

>

> How is this workable? I left it as of_match_device() because the value

> returned may be 0 for the enum and that looks the same as NULL.


This function is used for the DT case only, so there will always be a match.
Hence you can do devid = (int)(uintptr_t)of_device_get_match_data(dev).

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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

Patch

diff --git a/drivers/mailbox/qcom-apcs-ipc-mailbox.c b/drivers/mailbox/qcom-apcs-ipc-mailbox.c
index eeebafd546e5..10557a950c2d 100644
--- a/drivers/mailbox/qcom-apcs-ipc-mailbox.c
+++ b/drivers/mailbox/qcom-apcs-ipc-mailbox.c
@@ -45,6 +45,12 @@  static const struct mbox_chan_ops qcom_apcs_ipc_ops = {
 	.send_data = qcom_apcs_ipc_send_data,
 };
 
+static const struct of_device_id apcs_clk_match_table[] = {
+	{ .compatible = "qcom,msm8916-apcs-kpss-global", },
+	{ .compatible = "qcom,qcs404-apcs-apps-global", },
+	{}
+};
+
 static int qcom_apcs_ipc_probe(struct platform_device *pdev)
 {
 	struct qcom_apcs_ipc *apcs;
@@ -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[] = {
-		{ .compatible = "qcom,msm8916-apcs-kpss-global", },
-		{ .compatible = "qcom,qcs404-apcs-apps-global", },
-		{}
-	};
 
 	apcs = devm_kzalloc(&pdev->dev, sizeof(*apcs), GFP_KERNEL);
 	if (!apcs)