linux-kernel - Re: [PATCH 3/3] pwm: New driver to support PWM driven LEDs on TWL4030/6030 series of PMICs

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Date:	Thu, 8 Nov 2012 08:34:31 +0100
From:	Péter Ujfalusi <peter.ujfalusi@...com>
To:	Grazvydas Ignotas <notasas@...il.com>
CC:	Thierry Reding <thierry.reding@...onic-design.de>,
	Tero Kristo <t-kristo@...com>, <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>
Subject: Re: [PATCH 3/3] pwm: New driver to support PWM driven LEDs on TWL4030/6030
 series of PMICs

On 11/07/2012 07:12 PM, Grazvydas Ignotas wrote:
>> +static int twl4030_pwmled_config(struct pwm_chip *chip, struct pwm_device *pwm,
>> +                             int duty_ns, int period_ns)
>> +{
>> +       int duty_cycle = (duty_ns * TWL4030_LED_MAX) / period_ns;
>> +       u8 on_time;
>> +       u8 pwm_config[2];
>> +       int base, ret;
>> +
>> +       if (duty_cycle >= TWL4030_LED_MAX)
>> +               on_time = TWL4030_LED_MAX;
>> +       else if (!duty_cycle)
>> +               on_time = TWL4030_LED_MAX - 1;
>> +       else
>> +               on_time = TWL4030_LED_MAX - duty_cycle;
>> +
>> +       base = pwm->hwpwm * 2 + TWL4030_PWMA_REG;
>> +
>> +       pwm_config[0] = on_time;
>> +       pwm_config[1] = TWL4030_LED_MAX;
>> +
>> +       ret = twl_i2c_write(TWL4030_MODULE_LED, pwm_config, base, 2);
> 
> Shouldn't this use TWL4030_MODULE_PWMA and TWL4030_MODULE_PWMB as
> first argument? I can guess it works your way too, but
> TWL4030_MODULE_PWMx would match the TRM better.

I don't have strong opinion regarding to this. You mean changing from:

base = pwm->hwpwm * 2 + TWL4030_PWMA_REG;
ret = twl_i2c_write(TWL4030_MODULE_LED, pwm_config, base, 2);

to:

if (pwm->hwpwm)
	module = TWL4030_MODULE_PWMB;
else
	module = TWL4030_MODULE_PWMA;
ret = twl_i2c_write(module, pwm_config, 0, 2);

But I want to note that I'm currently trying to clean up the mess around
twl-core. In my view we have quite a bit of redundancy in there. The PWM A/B
is for driving the LED A/B outputs. We should have only these modules for
PWM/LED in twl-core:
TWL_MODULE_PWM - offset for PWM0ON register in twl4030 and PWM1ON for twl6030
TWL_MODULE_LED - offset for LEDEN register in twl4030 and LED_PWM_CTRL1
		 for twl6030

>From here the driver can figure out what to do IMHO.

There's no need to have separate TWL 'modules' for:
TWL4030_BASEADD_PWM0
TWL4030_BASEADD_PWM1
TWL4030_BASEADD_PWMA
TWL4030_BASEADD_PWMB

-- 
Péter
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