Re: [PATCH 4/9] drivers/pwm: Add helper to configure pwm using clock divisor and duty percent

From: Shobhit Kumar <shobhit.kumar@linux.intel.com>
To: Thierry Reding <thierry.reding@gmail.com>,
	Shobhit Kumar <shobhit.kumar@intel.com>
Cc: Alexandre Courbot <gnurou@gmail.com>,
	Samuel Ortiz <sameo@linux.intel.com>,
	Jani Nikula <jani.nikula@intel.com>,
	intel-gfx <intel-gfx@lists.freedesktop.org>,
	Daniel Vetter <daniel.vetter@intel.com>,
	Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH 4/9] drivers/pwm: Add helper to configure pwm using clock divisor and duty percent
Date: Wed, 01 Apr 2015 11:58:50 +0530	[thread overview]
Message-ID: <551B9022.107@linux.intel.com> (raw)
In-Reply-To: <20150324082357.GA17183@ulmo.nvidia.com>

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On 03/24/2015 01:53 PM, Thierry Reding wrote:
> On Fri, Mar 13, 2015 at 07:28:02PM +0530, Shobhit Kumar wrote:
>> Some chips instead of using period_ns and duty_ns can be
>> configured using the clock divisor and duty percent. Adds an
>> alternative configuration method for such chips
> 
> I don't see a need to introduce this alternative configuration 
> mechanism. Most, of not all, of the other drivers program a clock 
> divisor and some percentage of the duty cycle as well and it should
> be easy to convert to that internally from the period and
> duty_cycle parameters that you get in ->config().

Perhaps. Probably I misunderstood but as per Documentation/pwm.txt, it
is suggested that rather than calculating in the driver, we can add
additional helpers. So I tried doing just that. And it also means that
the consumer(which is directly aware of the percent it wants) has to
do the calculation and pass as ns values and we internally again
convert back to percentage ?

> 
> Adding an alternative means of configuring the PWM also means that
> every user driver now potentially needs to support both the
> traditional and the alternative way because PWM providers may not
> implement both.

I just assumed either or implementation should suffice. Even in my
implementation the error checks assumes either of the two should be
available else to fail the pwmchip_add

Regards
Shobhit

> 
> Thierry
> 
> 
> 
> _______________________________________________ Intel-gfx mailing
> list Intel-gfx@lists.freedesktop.org 
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
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