>> >> >> On 28 of September 2010 10:40:42 Arun Murthy wrote: >> >> >> > 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 >> >> >> > be exposing the same set of function name as in >> >> include/linux/pwm.h. >> >> >> > As a result build fails. >> >> >> >> >> >> Which build fails? One with multi-SoC support? Please be more >> >> specific. >> >> > 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. >> > You are right, there is only one pwm module in twl4030/twl6030 and this module might have any number or pwm's line PWM1, PWM2, PWM3 etc. > My consideration is when you have two separate pwm modules on different soc. Its not in case of OMAP boards. But that was just an example that I > gave. > > Let me be more specific, consider an environment where there is an APE and Power Management subsystem(separate IC but on same board/platform) > APE has a pwm module and Power Management SubSystem also has pwm module. Both are part of the platform. > Not there exists two drivers in a single platform and both of them are enabled. Building such a kernel results in re-declaration build error. > Is this something specific to ST chipsets or do you know of any other chips which might use this feature. Thanks Hemanth
