[PATCH] backlight: add PWM dependencies

[Arnd Bergmann]

On Thursday 06 February 2014, Jingoo Han wrote:
> In the case of "CONFIG_HAVE_PWM=y && CONFIG_PWM=n", it makes
> the problem.
> 
> The HAVE_PWM symbol is only for legacy platforms that provide
> the PWM API without using the generic framework. PXA looks to
> use the generic PWM framework. Then, how about removing
> "select HAVE_PWM" from PXA as below?
> 

I think this is correct, but we may need additional patches. I notice
that INPUT_MAX8997_HAPTIC and INPUT_PWM_BEEPER have a dependency on
HAVE_PWM at the moment, so those two drivers become impossible
to select after your change.

There is also one use of HAVE_PWM outside of PXA, for ARCH_LPC32XX.
This one seems to have the same problem.

Finally, I have recently encountered a couple of drivers
(BACKLIGHT_LM3630A, BACKLIGHT_LP855X, BACKLIGHT_LP8788) that use
the PWM interfaces but are missing a 'depends on PWM'. This is
strictly speaking a different problem, but we could try to solve
it at the same time.

	Arnd