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

To: Hemanth V <>
Subject: Re: [PATCH 1/7] pwm: Add pwm core driver
From: Samuel Ortiz <>
Date: Tue, 28 Sep 2010 15:06:11 +0200
Cc: Arun Murthy <>,, Andrew Morton <>,,,,,,,,,,,,
In-reply-to: <040c01cb5f0c$29bcb3b0$LocalHost@wipblrx0099946>
References: <> <> <040c01cb5f0c$29bcb3b0$LocalHost@wipblrx0099946>
User-agent: Mutt/1.5.20 (2009-06-14)
On Tue, Sep 28, 2010 at 06:23:24PM +0530, Hemanth V wrote:
> ----- Original Message ----- From: "Arun Murthy"
> <>
> >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 in case of multi soc environments where each soc
> >has a pwm device in it.
> This seems very specific to ST environment,  
No it's not. It's an issue Arun has hit while enabling one of the ST MFD chip,
but he's tackling a generic issue.

> looking at the driver list from
> ( [PATCH 4/7] pwm: Align existing pwm drivers with pwm-core ) it seems
> most multi SOC environments might support PWM in either one of the SOC.
> arch/arm/plat-mxc/pwm.c
> arch/arm/plat-pxa/pwm.c
> arch/arm/plat-samsung/pwm.c
> arch/mips/jz4740/pwm.c
> drivers/mfd/twl6030-pwm.c
> Unless people have examples of other SOCs which might use this,
> the better approach might be to go for a custom driver rather than changing
> the framework.
I wouldn't call the current pwm code a framework. It's a bunch of header
definitions that happens to work in the specific case of 1 pwm per
sub architecture.
What Arun is proposing is an actual framework. And it seems to be clean and
simple enough.


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