[PATCH] backlight: add PWM dependencies
jg1.han at samsung.com
Thu Feb 6 01:49:33 EST 2014
On Wednesday, February 05, 2014 5:58 PM, Linus Walleij wrote:
> On Wed, Feb 5, 2014 at 6:01 AM, Jingoo Han <jg1.han at samsung.com> wrote:
> > 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.
> So you may think but it does happen :-)
> I reproduced this with the defconfig for ARM pxa255-idp and enabling
> all boards for that platform, then enabling all available backlight drivers
> as compiled-in objects (y).
However, I cannot reproduce it with mainline kernel 3.14-rc1.
1. make pxa255-idp_defconfig
2. Enabling all boards
(System Type -> Intel PXA2xx/PXA3xx Implementations -> ...)
3. Enabling all available backlight drivers as compiled-in objects (y)
In this case, the LM3630A and LP855X backlight drivers are compiled
properly as below:
Would you check it with mainline kernel 3.14-rc1?
If the errors happen, please attach the .config file.
> > ./include/linux/pwm.h
> > #if IS_ENABLED(CONFIG_PWM) || IS_ENABLED(CONFIG_HAVE_PWM)
> > .....
> > #else
> Hm PXA that I am using defines CONFIG_HAVE_PWM, but doesn't
> provide the required signatures (pwm_config/pwm_disable/pwm_enable).
> One of two things is wrong:
> - Either the PXA platform is breaking the CONFIG_HAVE_PWM
> contract by not providing pwm_config/pwm_disable/pwm_enable
> functions. Then HAVE_PWM should be removed from the PXA
> Kconfig selects.
> - There is no such contract that these functions must exist if
> CONFIG_HAVE_PWM is defined, and the
> #if IS_ENABLED(CONFIG_HAVE_PWM)
> should be removed from <linux/pwm.h>
> Does anyone know which one it is?
> PWM subsystem maintainer? :-)
> Linus Walleij
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