On Tuesday, February 04, 2014 9:57 PM, Linus Walleij wrote: > > In some compilations the LM3630A and LP855X backlight drivers > fail like this: > > drivers/built-in.o: In function `lm3630a_pwm_ctrl': > drivers/video/backlight/lm3630a_bl.c:168: undefined reference to `pwm_config' > drivers/video/backlight/lm3630a_bl.c:172: undefined reference to `pwm_disable' > drivers/video/backlight/lm3630a_bl.c:170: undefined reference to `pwm_enable' > drivers/built-in.o: In function `lp855x_pwm_ctrl': > drivers/video/backlight/lp855x_bl.c:249: undefined reference to `pwm_config' > drivers/video/backlight/lp855x_bl.c:253: undefined reference to `pwm_disable' > drivers/video/backlight/lp855x_bl.c:251: undefined reference to `pwm_enable' > > This is because both drivers depend on the PWM framework, so > add this dependency to their Kconfig entries.
However, even though, when CONFIG_PWM is not enabled, the problem should not happen. pwm_config(),pwm_disable(), and pwm_enable() are already defined for CONFIG_PWM=n case as below. ./include/linux/pwm.h #if IS_ENABLED(CONFIG_PWM) || IS_ENABLED(CONFIG_HAVE_PWM) ..... #else static inline struct pwm_device *pwm_request(int pwm_id, const char *label) { return ERR_PTR(-ENODEV); } static inline void pwm_free(struct pwm_device *pwm) { } static inline int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) { return -EINVAL; } static inline int pwm_enable(struct pwm_device *pwm) { return -EINVAL; } static inline void pwm_disable(struct pwm_device *pwm) { } #endif Is there 'drivers/pwm/core.o'? I reproduced this problem by commenting core.o with CONFIG_PWM=y. .config CONFIG_PWM=y ./drivers/pwm/Makefile @@ -1,4 +1,4 @@ -obj-$(CONFIG_PWM) += core.o +#obj-$(CONFIG_PWM) += core.o In this case, the following build errors happen. Even though, CONFIG_PWM is enabled, the same errors happen. Would you give me the more detailed information? Ex. how to reproduce the problem. drivers/built-in.o: In function `lm3630a_pwm_ctrl': drivers/video/backlight/lm3630a_bl.c:168: undefined reference to `pwm_config' drivers/video/backlight/lm3630a_bl.c:172: undefined reference to `pwm_disable' drivers/video/backlight/lm3630a_bl.c:170: undefined reference to `pwm_enable' drivers/built-in.o: In function `lm3630a_probe': drivers/video/backlight/lm3630a_bl.c:422: undefined reference to `devm_pwm_get' drivers/built-in.o: In function `lp855x_pwm_ctrl': drivers/video/backlight/lp855x_bl.c:249: undefined reference to `pwm_config' drivers/video/backlight/lp855x_bl.c:253: undefined reference to `pwm_disable' drivers/video/backlight/lp855x_bl.c:251: undefined reference to `pwm_enable' drivers/video/backlight/lp855x_bl.c:242: undefined reference to `devm_pwm_get' Thank you. Best regards, Jingoo Han > > Signed-off-by: Linus Walleij <linus.wall...@linaro.org> > --- > drivers/video/backlight/Kconfig | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig > index 5a3eb2ecb525..0604c3348761 100644 > --- a/drivers/video/backlight/Kconfig > +++ b/drivers/video/backlight/Kconfig > @@ -371,6 +371,7 @@ config BACKLIGHT_AAT2870 > config BACKLIGHT_LM3630A > tristate "Backlight Driver for LM3630A" > depends on BACKLIGHT_CLASS_DEVICE && I2C > + depends on PWM > select REGMAP_I2C > help > This supports TI LM3630A Backlight Driver > @@ -387,6 +388,7 @@ config BACKLIGHT_LM3639 > config BACKLIGHT_LP855X > tristate "Backlight driver for TI LP855X" > depends on BACKLIGHT_CLASS_DEVICE && I2C > + depends on PWM > help > This supports TI LP8550, LP8551, LP8552, LP8553, LP8555, LP8556 and > LP8557 backlight driver. > -- > 1.8.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/