linux-kernel - Re: [PATCH RFT 1/2] regulator: ab8500: Fix set voltage for AB8540_LDO

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Message-ID: <516D2EB7.8010608@stericsson.com>
Date:	Tue, 16 Apr 2013 12:57:59 +0200
From:	Bengt Jönsson <bengt.g.jonsson@...ricsson.com>
To:	Axel Lin <axel.lin@...ics.com>
Cc:	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Lee Jones <lee.jones@...aro.org>,
	Yvan FILLION <yvan.fillion@...ricsson.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFT 1/2] regulator: ab8500: Fix set voltage for AB8540_LDO_AUX3

On 04/10/2013 08:40 AM, Axel Lin wrote:
> When setting voltage for AB8540_LDO_AUX3, current code only updates one of
> info->voltage_reg and info->expand_register registers which is wrong.
> To ensure we set to correct voltage, it always needs to clear or set
> expand_register.voltage_mask bit of expand_register.
The original code is wrong. It is not possible to leave 3.05 V once set.

The function of the expand register bit is the following (from the user 
manual):
0: VAUX3 output voltage is determined by Vaux3Sel bit settings in 
register VldoCVaux3Sel
1: VAUX3 output voltage is set to 3.05 V regardless of Vaux3Sel settings 
in register VldoCVaux3Sel
(VldoCVaux3Sel is the register at 0x0421)

So when going to 3.05 V I would like to set the bit as you are doing. 
But when leaving 3.05 V for another voltage I would prefer setting the 
target voltage before clearing the expand register bit.
>
> Signed-off-by: Axel Lin <axel.lin@...ics.com>
> ---
>   drivers/regulator/ab8500.c |   55 ++++++++++++++++++++++++++++----------------
>   1 file changed, 35 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/regulator/ab8500.c b/drivers/regulator/ab8500.c
> index 9ebd131..222a63e 100644
> --- a/drivers/regulator/ab8500.c
> +++ b/drivers/regulator/ab8500.c
> @@ -605,39 +605,54 @@ static int ab8540_aux3_regulator_set_voltage_sel(struct regulator_dev *rdev,
>   {
>   	int ret;
>   	struct ab8500_regulator_info *info = rdev_get_drvdata(rdev);
> -	u8 regval;
> +	u8 regval, regval_expand;
>   
>   	if (info == NULL) {
>   		dev_err(rdev_get_dev(rdev), "regulator info null pointer\n");
>   		return -EINVAL;
>   	}
>   
> -	if (selector >= info->expand_register.voltage_limit) {
> -		/* Vaux3 bit4 has different layout */
> -		regval = (u8)selector << info->expand_register.voltage_shift;
> -		ret = abx500_mask_and_set_register_interruptible(info->dev,
> -					info->expand_register.voltage_bank,
> -					info->expand_register.voltage_reg,
> -					info->expand_register.voltage_mask,
> -					regval);
> -	} else {
> -		/* set the registers for the request */
> -		regval = (u8)selector << info->voltage_shift;
> -		ret = abx500_mask_and_set_register_interruptible(info->dev,
> +	if (selector >= info->expand_register.voltage_limit)
> +		regval_expand = info->expand_register.voltage_mask;
> +	else
> +		regval_expand = 0;
> +
> +	ret = abx500_mask_and_set_register_interruptible(info->dev,
> +				info->expand_register.voltage_bank,
> +				info->expand_register.voltage_reg,
> +				info->expand_register.voltage_mask,
> +				regval_expand);
> +	if (ret < 0) {
> +		dev_err(rdev_get_dev(rdev),
> +			"couldn't set expand voltage reg for regulator\n");
> +		return ret;
> +	}
> +
> +	dev_vdbg(rdev_get_dev(rdev),
> +		 "%s-set_voltage expand (bank, reg, mask, value): 0x%x, 0x%x, 0x%x, 0x%x\n",
> +		 info->desc.name, info->expand_register.voltage_bank,
> +		 info->expand_register.voltage_reg,
> +		 info->expand_register.voltage_mask, regval_expand);
> +
> +	if (selector >= info->expand_register.voltage_limit)
> +		return 0;
> +
> +	regval = (u8)selector << info->voltage_shift;
> +	ret = abx500_mask_and_set_register_interruptible(info->dev,
>   				info->voltage_bank, info->voltage_reg,
>   				info->voltage_mask, regval);
> -	}
> -	if (ret < 0)
> +	if (ret < 0) {
>   		dev_err(rdev_get_dev(rdev),
>   			"couldn't set voltage reg for regulator\n");
> +		return ret;
> +	}
>   
>   	dev_vdbg(rdev_get_dev(rdev),
> -			"%s-set_voltage (bank, reg, mask, value): 0x%x, 0x%x, 0x%x,"
> -			" 0x%x\n",
> -			info->desc.name, info->voltage_bank, info->voltage_reg,
> -			info->voltage_mask, regval);
> +		 "%s-set_voltage (bank, reg, mask, value): 0x%x, 0x%x, 0x%x, 0x%x\n",
> +		 info->desc.name, info->voltage_bank, info->voltage_reg,
> +		 info->voltage_mask, regval);
>   
> -	return ret;
> +	return 0;
>   }
>   
>   static struct regulator_ops ab8500_regulator_volt_mode_ops = {

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