linux-kernel - RE: [PATCH V2] regulator: DA9211 : new regulator driver

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Message-ID: <0ACAE736BB7A70499F1D8D5E6AC1854C0196DD18DE@NB-EX-MBX01.diasemi.com>
Date:	Mon, 2 Jun 2014 02:43:09 +0000
From:	"Opensource [James Seong-Won Ban]" <James.Ban.opensource@...semi.com>
To:	Mark Brown <broonie@...nel.org>,
	"Opensource [James Seong-Won Ban]" <James.Ban.opensource@...semi.com>
CC:	Liam Girdwood <lgirdwood@...il.com>,
	Support Opensource <Support.Opensource@...semi.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Guennadi Liakhovetski <g.liakhovetski@....de>,
	David Dajun Chen <david.chen@...semi.com>
Subject: RE: [PATCH V2] regulator: DA9211 : new regulator driver



> -----Original Message-----
> From: Mark Brown [mailto:broonie@...nel.org]
> Sent: Monday, June 02, 2014 4:02 AM
> To: Opensource [James Seong-Won Ban]
> Cc: Liam Girdwood; Support Opensource; LKML; Guennadi Liakhovetski;
> David Dajun Chen
> Subject: Re: [PATCH V2] regulator: DA9211 : new regulator driver
> 
> On Mon, May 19, 2014 at 02:45:51AM +0100, Opensource [James Seong-Won
> Ban] wrote:
> 
> > This is the driver for the Dialog DA9211 Multi-phase 12A DC-DC Buck
> > Converter regulator. It communicates via an I2C bus to the device.
> 
> I'm still really not convinced that the whole handling of the A and B settings is
> doing what it's supposed to be doing.  Like I said before I know another one
> of your drivers is doing something similar (and not sharing the code!) but
> still...
> 
> It looks like the driver is basically written so that register set A must be used
> when Linux is running and set B must be used in suspend mode but not
> everything seems joined up and consistent.
> 
> > Signed-off-by: Opensource [James Seong-Won Ban]
> > <james.ban.opensource@...semi.com>
> 
> Please just use your name in signoffs, the "Opensource []" garbage that your
> mail system inserts isn't helping.
it will be fixed in next PATCH.
> 
> > +static int da9211_regulator_get_voltage_sel(struct regulator_dev
> > +*rdev) {
> 
> > +	/*
> > +	 * There are two voltage register set A & B for voltage ramping but
> > +	 * either one of then can be active therefore we first determine
> > +	 * the active register set.
> > +	 */
> > +	ret = regmap_read(chip->regmap, info->conf.reg, &data);
> > +	if (ret < 0)
> > +		return ret;
> 
> This appears to be picking the active register set...
> 
> > +	/*
> > +	 * Regulator register set A/B is not selected through GPIO therefore
> > +	 * we use default register set A for voltage ramping.
> > +	 */
> > +	if (regulator->reg_rselect == DA9211_RSEL_NO_GPIO) {
> > +		/* Select register set A */
> > +		ret = regmap_update_bits(chip->regmap, info->conf.reg,
> > +					info->conf.sel_mask,
> > +					DA9211_VBUCKA_SEL_A);
> > +		if (ret < 0)
> > +			return ret;
> > +
> > +		/* Set the voltage */
> > +		return regmap_update_bits(chip->regmap, info->volt.reg_a,
> > +					 info->volt.v_mask, selector);
> > +	}
> 
> This forces to register set A.
> 
> > +	/*
> > +	 * Here regulator register set A/B is selected through GPIO.
> > +	 * Therefore we first determine the selected register set A/B and
> > +	 * then set the desired voltage for that register set A/B.
> > +	 */
> > +	ret = regmap_read(chip->regmap, info->conf.reg, &data);
> > +	if (ret < 0)
> > +		return ret;
> 
> We don't appear to be controlling this GPIO - this then assumes that the
> GPIO can only be used for selecting suspend mode but doesn't impose any
> restrictions on this.
In this device, the values of selection register for A/B voltage are changed 
automatically  if the status of GPIO is changed.
So it is possible to know the status of GPIO through the value of register.
> 
> > +static int da9211_regulator_set_suspend_voltage(struct regulator_dev
> *rdev,
> > +						int uV)
> > +{
> > +	struct da9211_regulator *regulator = rdev_get_drvdata(rdev);
> > +	struct da9211_regulator_info *info = regulator->info;
> > +	struct da9211 *chip = regulator->da9211;
> > +	int ret;
> > +
> > +	/* Select register set B for suspend voltage ramping. */
> > +	if (regulator->reg_rselect == DA9211_RSEL_NO_GPIO) {
> > +		ret = regmap_update_bits(chip->regmap, info->conf.reg,
> > +					info->conf.sel_mask,
> > +					DA9211_VBUCKA_SEL_B);
> > +		if (ret < 0)
> > +			return ret;
> > +	}
> 
> This appears to immediately change the active register set to set B which as I
> said previously is broken; we may not be suspended yet and clearly we
> haven't actually applied the desired setting yet either.
Your suggestion is correct. The code for the change of the active register 
in the function should be removed. I will send PATCH again.
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