[PATCH 1/7] pwm: Add pwm core driver

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On 28 of September 2010 10:40:42 Arun Murthy wrote:

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The existing pwm based led and backlight driver makes use of the
pwm(include/linux/pwm.h). So all the board specific pwm drivers

will

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be exposing the same set of function name as in

include/linux/pwm.h.

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As a result build fails.

Which build fails? One with multi-SoC support? Please be more

specific.

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Sure will add this in v2.

Could you clarify for the benefit of all, which specific issues you are
trying to address with this patch series

1. Now since all the pwm driver export same set of function(pwm_enable, pwm_disable,..), if it happens that there are two pwm driver enabled this
leads to re-declaration and results in build failure. The proper way to handle this would be to have a pwm core function, and let all the pwm
drivers register to the pwm core driver.
2. The above scenario also occurs in place of multi-soc environment. Lets say OMAP has a pwm module and that is being used for primary lcd backlight
and twl has a backlight that is being used for controlling the charging led brightness. In this case there exists 2 pwm drivers and one pwm driver
will be used by pwm_bl.c and other by leds-pwm.c

Speaking specifically of OMAP4, twl6030 supports multiple PWMs i.e for display/keypad backlight, charging
led. But there should not be need for multiple drivers since twl6030-pwm should be able to support
all these (currently it doesnot though). So there would single pwm_enable, pwm_disable exported and driver
internally takes care configuring the correct PWM based on id. Would it not be similar
situation for other hardware also.

Thanks
Hemanth