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

To: Arun MURTHY <>
Subject: Re: [PATCH 1/7] pwm: Add pwm core driver
From: Trilok Soni <>
Date: Fri, 1 Oct 2010 12:17:32 +0530
Cc: Lars-Peter Clausen <>, "" <>, "" <>, Andrew Morton <>, "" <>, "" <>, "" <>, Marek Vasut <>, "" <>, Samuel Ortiz <>, "" <>, "" <>, "" <>, "" <>, Linus WALLEIJ <>, Mattias WALLIN <>, linux-arm-kernel <>, "" <>, STEricsson_nomadik_linux <>, Bill Gatliff <>
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Hi Arun,

On Fri, Oct 1, 2010 at 8:55 AM, Arun MURTHY <> wrote:
> Hi Trilok,
>> Hi Arun,
>> Adding Bill Gatliff (anyway, CC list already crowded)
>> On Wed, Sep 29, 2010 at 10:19 AM, Arun MURTHY
>> <> wrote:
>> >> Arun MURTHY wrote:
>> >> >>>> Shouldn't PWM_DEVICES select HAVE_PWM?
>> >> >>>
>> >> >>> No not required, the entire concept is to remove HAVE_PWM and
>> use
>> >> >> PWM_CORE.
>> There is already nice and clean framework written by Bill for PWM, if
>> you grep the LKML and linux-embedded mailing list archive then you
>> will get his patches, and it seems that he had promised to send the
>> updated version few week back, but not heard from him (may be because
>> he was travelling as per FB status).
>> Please evaluate that framework too.
> Thanks for this information, I did search in linux-embedded mailing list
> archive. Below are my views on that patch set.
> Many of the functions that has been defined in pwm core driver
> written by Bill Gatliff is not being used by the most of the pwm drivers
> except Atmel PWM driver. I rather felt the pwm core driver was an attempt
> made to generalize the Atmel pwm driver.
> And moreover this was posted long back somewhere in the beginning of this
> year i.e Feb and the thread is dead thereafter.
> This patch has been submitted focusing all the existing pwm drivers and
> only these are the functions that are being used by pwm drivers.
> This patch set also included patch to align all the existing pwm driver
> with the pwm core driver.
> So it is an attempt to generalize most of the pwm drivers and
> conclude with a pwm core driver.

I don't agree that Bill had only atmel drivers view. The PWM framework
was discussed in-depth and at that time reviewers also requested once
to provide more example drivers using these drivers, someone said "we
atleast need three drivers as rule of thumb". Let's wait until Bill
reviews your framework, I am sure we don't need to end up the same
problems faced by Bill while designing that framework in your code

---Trilok Soni

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