linux-kernel - RE: [PATCH 2/2] mfd: da9063: Make vbcore registers volatile

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Message-ID: <DB9PR10MB4652A195CDB7E237A0D87F6180619@DB9PR10MB4652.EURPRD10.PROD.OUTLOOK.COM>
Date:   Wed, 24 Nov 2021 09:34:42 +0000
From:   Adam Thomson <Adam.Thomson.Opensource@...semi.com>
To:     Andrej Picej <andrej.picej@...ik.com>,
        Support Opensource <Support.Opensource@...semi.com>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "s.riedmueller@...tec.de" <s.riedmueller@...tec.de>
Subject: RE: [PATCH 2/2] mfd: da9063: Make vbcore registers volatile

On 24 November 2021 07:00, Andrej Picej wrote:

> From: Stefan Riedmueller <s.riedmueller@...tec.de>
> 
> The VBCORE1_A and VBCORE2_A registers are used to set the desired output
> voltage of the BCORE 1 and 2 buck regulators. These values can be critical
> if used as input for core voltages. Thus make them volatile so they do not
> get cached.

I don't understand the need for this change. What is this fixing? As I
understand it the registers in question aren't volatile so should persist.

> Signed-off-by: Stefan Riedmueller <s.riedmueller@...tec.de>
> Signed-off-by: Andrej Picej <andrej.picej@...ik.com>
> ---
>  drivers/mfd/da9063-i2c.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/mfd/da9063-i2c.c b/drivers/mfd/da9063-i2c.c
> index 343ed6e96d87..8a3629c30382 100644
> --- a/drivers/mfd/da9063-i2c.c
> +++ b/drivers/mfd/da9063-i2c.c
> @@ -161,6 +161,7 @@ static const struct regmap_range
> da9063_ad_volatile_ranges[] = {
>  	regmap_reg_range(DA9063_REG_ADC_RES_L,
> DA9063_AD_REG_SECOND_D),
>  	regmap_reg_range(DA9063_REG_SEQ, DA9063_REG_SEQ),
>  	regmap_reg_range(DA9063_REG_EN_32K, DA9063_REG_EN_32K),
> +	regmap_reg_range(DA9063_REG_VBCORE2_A,
> DA9063_REG_VBCORE2_A),
>  	regmap_reg_range(DA9063_AD_REG_MON_REG_5,
> DA9063_AD_REG_MON_REG_6),
>  };
> 
> @@ -206,6 +207,7 @@ static const struct regmap_range
> da9063_bb_da_volatile_ranges[] = {
>  	regmap_reg_range(DA9063_REG_ADC_RES_L,
> DA9063_BB_REG_SECOND_D),
>  	regmap_reg_range(DA9063_REG_SEQ, DA9063_REG_SEQ),
>  	regmap_reg_range(DA9063_REG_EN_32K, DA9063_REG_EN_32K),
> +	regmap_reg_range(DA9063_REG_VBCORE2_A,
> DA9063_REG_VBCORE2_A),
>  	regmap_reg_range(DA9063_BB_REG_MON_REG_5,
> DA9063_BB_REG_MON_REG_6),
>  };
> 
> --
> 2.25.1