diff mbox series

[10/13] cpufreq: powernow-k8: Make use of known set but not used variables

Message ID 20200714145049.2496163-11-lee.jones@linaro.org (mailing list archive)
State New, archived
Headers show
Series Rid W=1 warnings in CPUFreq | expand

Commit Message

Lee Jones July 14, 2020, 2:50 p.m. UTC
If we fail to use a variable, even a 'dummy' one, then the compiler
complains that it is set but not used.  We know this is fine, so we
set it to its own value here.

Fixes the following W=1 kernel build warning(s):

 drivers/cpufreq/powernow-k8.c: In function ‘pending_bit_stuck’:
 drivers/cpufreq/powernow-k8.c:89:10: warning: variable ‘hi’ set but not used [-Wunused-but-set-variable]
 89 | u32 lo, hi;
 | ^~
 drivers/cpufreq/powernow-k8.c: In function ‘core_voltage_pre_transition’:
 drivers/cpufreq/powernow-k8.c:285:14: warning: variable ‘lo’ set but not used [-Wunused-but-set-variable]
 285 | u32 maxvid, lo, rvomult = 1;
 | ^~

Cc: Andreas Herrmann <herrmann.der.user@googlemail.com>
Cc: Dominik Brodowski <linux@brodo.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Paul Devriendt <paul.devriendt@amd.com>
Cc: Mark Langsdorf <mark.langsdorf@amd.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/cpufreq/powernow-k8.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Rafael J. Wysocki July 14, 2020, 5:43 p.m. UTC | #1
On Tue, Jul 14, 2020 at 4:51 PM Lee Jones <lee.jones@linaro.org> wrote:
>
> If we fail to use a variable, even a 'dummy' one, then the compiler
> complains that it is set but not used.  We know this is fine, so we
> set it to its own value here.
>
> Fixes the following W=1 kernel build warning(s):
>
>  drivers/cpufreq/powernow-k8.c: In function ‘pending_bit_stuck’:
>  drivers/cpufreq/powernow-k8.c:89:10: warning: variable ‘hi’ set but not used [-Wunused-but-set-variable]
>  89 | u32 lo, hi;
>  | ^~
>  drivers/cpufreq/powernow-k8.c: In function ‘core_voltage_pre_transition’:
>  drivers/cpufreq/powernow-k8.c:285:14: warning: variable ‘lo’ set but not used [-Wunused-but-set-variable]
>  285 | u32 maxvid, lo, rvomult = 1;
>  | ^~
>
> Cc: Andreas Herrmann <herrmann.der.user@googlemail.com>
> Cc: Dominik Brodowski <linux@brodo.de>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Paul Devriendt <paul.devriendt@amd.com>
> Cc: Mark Langsdorf <mark.langsdorf@amd.com>
> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> ---
>  drivers/cpufreq/powernow-k8.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
> index 3984959eed1d5..b76df81044c4f 100644
> --- a/drivers/cpufreq/powernow-k8.c
> +++ b/drivers/cpufreq/powernow-k8.c
> @@ -89,6 +89,7 @@ static int pending_bit_stuck(void)
>         u32 lo, hi;
>
>         rdmsr(MSR_FIDVID_STATUS, lo, hi);
> +       hi &= hi; /* Silence set but not used warning */

Hmm.

What about using __always_unused for this?

>         return lo & MSR_S_LO_CHANGE_PENDING ? 1 : 0;
>  }
>
> @@ -292,6 +293,7 @@ static int core_voltage_pre_transition(struct powernow_k8_data *data,
>                 rvomult = 2;
>         rvosteps *= rvomult;
>         rdmsr(MSR_FIDVID_STATUS, lo, maxvid);
> +       lo &= lo; /* Silence set but not used warning */
>         maxvid = 0x1f & (maxvid >> 16);
>         pr_debug("ph1 maxvid=0x%x\n", maxvid);
>         if (reqvid < maxvid) /* lower numbers are higher voltages */
> --
> 2.25.1
>
Lee Jones July 14, 2020, 9:01 p.m. UTC | #2
On Tue, 14 Jul 2020, Rafael J. Wysocki wrote:

> On Tue, Jul 14, 2020 at 4:51 PM Lee Jones <lee.jones@linaro.org> wrote:
> >
> > If we fail to use a variable, even a 'dummy' one, then the compiler
> > complains that it is set but not used.  We know this is fine, so we
> > set it to its own value here.
> >
> > Fixes the following W=1 kernel build warning(s):
> >
> >  drivers/cpufreq/powernow-k8.c: In function ‘pending_bit_stuck’:
> >  drivers/cpufreq/powernow-k8.c:89:10: warning: variable ‘hi’ set but not used [-Wunused-but-set-variable]
> >  89 | u32 lo, hi;
> >  | ^~
> >  drivers/cpufreq/powernow-k8.c: In function ‘core_voltage_pre_transition’:
> >  drivers/cpufreq/powernow-k8.c:285:14: warning: variable ‘lo’ set but not used [-Wunused-but-set-variable]
> >  285 | u32 maxvid, lo, rvomult = 1;
> >  | ^~
> >
> > Cc: Andreas Herrmann <herrmann.der.user@googlemail.com>
> > Cc: Dominik Brodowski <linux@brodo.de>
> > Cc: Pavel Machek <pavel@ucw.cz>
> > Cc: Paul Devriendt <paul.devriendt@amd.com>
> > Cc: Mark Langsdorf <mark.langsdorf@amd.com>
> > Signed-off-by: Lee Jones <lee.jones@linaro.org>
> > ---
> >  drivers/cpufreq/powernow-k8.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
> > index 3984959eed1d5..b76df81044c4f 100644
> > --- a/drivers/cpufreq/powernow-k8.c
> > +++ b/drivers/cpufreq/powernow-k8.c
> > @@ -89,6 +89,7 @@ static int pending_bit_stuck(void)
> >         u32 lo, hi;
> >
> >         rdmsr(MSR_FIDVID_STATUS, lo, hi);
> > +       hi &= hi; /* Silence set but not used warning */
> 
> Hmm.
> 
> What about using __always_unused for this?

I didn't know you could use that for standard variables.

Will fix.

> >         return lo & MSR_S_LO_CHANGE_PENDING ? 1 : 0;
> >  }
> >
> > @@ -292,6 +293,7 @@ static int core_voltage_pre_transition(struct powernow_k8_data *data,
> >                 rvomult = 2;
> >         rvosteps *= rvomult;
> >         rdmsr(MSR_FIDVID_STATUS, lo, maxvid);
> > +       lo &= lo; /* Silence set but not used warning */
> >         maxvid = 0x1f & (maxvid >> 16);
> >         pr_debug("ph1 maxvid=0x%x\n", maxvid);
> >         if (reqvid < maxvid) /* lower numbers are higher voltages */
> >
diff mbox series

Patch

diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 3984959eed1d5..b76df81044c4f 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -89,6 +89,7 @@  static int pending_bit_stuck(void)
 	u32 lo, hi;
 
 	rdmsr(MSR_FIDVID_STATUS, lo, hi);
+	hi &= hi; /* Silence set but not used warning */
 	return lo & MSR_S_LO_CHANGE_PENDING ? 1 : 0;
 }
 
@@ -292,6 +293,7 @@  static int core_voltage_pre_transition(struct powernow_k8_data *data,
 		rvomult = 2;
 	rvosteps *= rvomult;
 	rdmsr(MSR_FIDVID_STATUS, lo, maxvid);
+	lo &= lo; /* Silence set but not used warning */
 	maxvid = 0x1f & (maxvid >> 16);
 	pr_debug("ph1 maxvid=0x%x\n", maxvid);
 	if (reqvid < maxvid) /* lower numbers are higher voltages */