drivers/bus: arm-cci: fix build warnings

When the arm-cci driver is enabled, but both CONFIG_ARM_CCI5xx_PMU and
CONFIG_ARM_CCI400_PMU are not, we get a warning about how parts of
the driver are never used:

drivers/perf/arm-cci.c:1454:29: error: 'cci_pmu_models' defined but not used [-Werror=unused-variable]
drivers/perf/arm-cci.c:693:16: error: 'cci_pmu_event_show' defined but not used [-Werror=unused-function]
drivers/perf/arm-cci.c:685:16: error: 'cci_pmu_format_show' defined but not used [-Werror=unused-function]

Marking all three functions as __maybe_unused avoids the warnings in
randconfig builds. I'm doing this lacking any ideas for a better fix.

Fixes: 3de6be7a3dd8 ("drivers/bus: Split Arm CCI driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 drivers/perf/arm-cci.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

-- 
2.9.0

On 28/05/18 16:41, Arnd Bergmann wrote:
> When the arm-cci driver is enabled, but both CONFIG_ARM_CCI5xx_PMU and

> CONFIG_ARM_CCI400_PMU are not, we get a warning about how parts of

> the driver are never used:

> 

> drivers/perf/arm-cci.c:1454:29: error: 'cci_pmu_models' defined but not used [-Werror=unused-variable]

> drivers/perf/arm-cci.c:693:16: error: 'cci_pmu_event_show' defined but not used [-Werror=unused-function]

> drivers/perf/arm-cci.c:685:16: error: 'cci_pmu_format_show' defined but not used [-Werror=unused-function]

> 

> Marking all three functions as __maybe_unused avoids the warnings in

> randconfig builds. I'm doing this lacking any ideas for a better fix.


Yeah, it's a bit of a silly configuration to allow building a driver 
supporting no PMU types, but I couldn't find a way to enforce "at least 
one sub-option enabled" logic without introducing mutually-exclusive 
dependencies which kbuild thinks are recursive.

An alternative would be to remove the CCI400/CCI5x0 configurability 
altogether - I've not not looked in detail at how much difference that 
actually makes.

Otherwise, as an immediate quick-fix:

Reviewed-by: Robin Murphy <robin.murphy@arm.com>


Thanks,
Robin.

> Fixes: 3de6be7a3dd8 ("drivers/bus: Split Arm CCI driver")

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

> ---

>   drivers/perf/arm-cci.c | 6 +++---

>   1 file changed, 3 insertions(+), 3 deletions(-)

> 

> diff --git a/drivers/perf/arm-cci.c b/drivers/perf/arm-cci.c

> index e6fadc8e1178..0d09d8e669cd 100644

> --- a/drivers/perf/arm-cci.c

> +++ b/drivers/perf/arm-cci.c

> @@ -120,9 +120,9 @@ enum cci_models {

>   

>   static void pmu_write_counters(struct cci_pmu *cci_pmu,

>   				 unsigned long *mask);

> -static ssize_t cci_pmu_format_show(struct device *dev,

> +static ssize_t __maybe_unused cci_pmu_format_show(struct device *dev,

>   			struct device_attribute *attr, char *buf);

> -static ssize_t cci_pmu_event_show(struct device *dev,

> +static ssize_t __maybe_unused cci_pmu_event_show(struct device *dev,

>   			struct device_attribute *attr, char *buf);

>   

>   #define CCI_EXT_ATTR_ENTRY(_name, _func, _config) 				\

> @@ -1451,7 +1451,7 @@ static int cci_pmu_offline_cpu(unsigned int cpu)

>   	return 0;

>   }

>   

> -static struct cci_pmu_model cci_pmu_models[] = {

> +static __maybe_unused struct cci_pmu_model cci_pmu_models[] = {

>   #ifdef CONFIG_ARM_CCI400_PMU

>   	[CCI400_R0] = {

>   		.name = "CCI_400",

>

On Tue, May 29, 2018 at 04:34:01PM +0100, Robin Murphy wrote:
> On 28/05/18 16:41, Arnd Bergmann wrote:

> >When the arm-cci driver is enabled, but both CONFIG_ARM_CCI5xx_PMU and

> >CONFIG_ARM_CCI400_PMU are not, we get a warning about how parts of

> >the driver are never used:

> >

> >drivers/perf/arm-cci.c:1454:29: error: 'cci_pmu_models' defined but not used [-Werror=unused-variable]

> >drivers/perf/arm-cci.c:693:16: error: 'cci_pmu_event_show' defined but not used [-Werror=unused-function]

> >drivers/perf/arm-cci.c:685:16: error: 'cci_pmu_format_show' defined but not used [-Werror=unused-function]

> >

> >Marking all three functions as __maybe_unused avoids the warnings in

> >randconfig builds. I'm doing this lacking any ideas for a better fix.

> 

> Yeah, it's a bit of a silly configuration to allow building a driver

> supporting no PMU types, but I couldn't find a way to enforce "at least one

> sub-option enabled" logic without introducing mutually-exclusive

> dependencies which kbuild thinks are recursive.

> 

> An alternative would be to remove the CCI400/CCI5x0 configurability

> altogether - I've not not looked in detail at how much difference that

> actually makes.

> 

> Otherwise, as an immediate quick-fix:

> 

> Reviewed-by: Robin Murphy <robin.murphy@arm.com>


I'll pick this one up into the arm perf tree.

Will