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Message-id: <1414405641.1674.1.camel@AMDC1943>
Date: Mon, 27 Oct 2014 11:27:21 +0100
From: Krzysztof Kozlowski <k.kozlowski@...sung.com>
To: Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Cc: Liam Girdwood <lgirdwood@...il.com>,
Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org,
Ben Dooks <ben-linux@...ff.org>,
Kukjin Kim <kgene.kim@...sung.com>,
Russell King <linux@....linux.org.uk>,
linux-arm-kernel@...ts.infradead.org,
linux-samsung-soc@...r.kernel.org, devicetree@...r.kernel.org,
Kyungmin Park <kyungmin.park@...sung.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
Chanwoo Choi <cw00.choi@...sung.com>
Subject: Re: [PATCH v4 2/3] regulator: max77686: Implement suspend disable for
some LDOs
On pon, 2014-10-27 at 11:08 +0100, Javier Martinez Canillas wrote:
> Hello Krzysztof,
>
> On 10/27/2014 10:44 AM, Krzysztof Kozlowski wrote:
> > Some LDOs of Maxim 77686 PMIC support disabling during system suspend
> > (LDO{2,6,7,8,10,11,12,14,15,16}). This was already implemented as part
> > of set_suspend_mode function. In that case the mode was one of:
> > - disable,
> > - normal mode,
> > - low power mode.
> > However there are no bindings for setting the mode during suspend.
> >
> > Add suspend disable for LDO regulators supporting this to the existing
> > max77686_buck_set_suspend_disable() function. This helps reducing
> > energy consumption during system sleep.
> >
> > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> > ---
> > drivers/regulator/max77686.c | 75 ++++++++++++++++++++++++++++++++++++++------
> > 1 file changed, 66 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/regulator/max77686.c b/drivers/regulator/max77686.c
> > index 3d0922051488..4b35c19c9286 100644
> > --- a/drivers/regulator/max77686.c
> > +++ b/drivers/regulator/max77686.c
> > @@ -87,18 +87,31 @@ struct max77686_data {
> > unsigned int opmode[MAX77686_REGULATORS];
> > };
> >
> > -/* Some BUCKS supports Normal[ON/OFF] mode during suspend */
> > -static int max77686_buck_set_suspend_disable(struct regulator_dev *rdev)
> > +/* Some BUCKs and LDOs supports Normal[ON/OFF] mode during suspend */
> > +static int max77686_set_suspend_disable(struct regulator_dev *rdev)
> > {
> > unsigned int val;
> > struct max77686_data *max77686 = rdev_get_drvdata(rdev);
> > int ret, id = rdev_get_id(rdev);
> >
> > - if (id == MAX77686_BUCK1)
> > + switch (id) {
> > + case MAX77686_BUCK1:
> > val = MAX77686_BUCK_OFF_PWRREQ;
> > - else
> > - val = MAX77686_BUCK_OFF_PWRREQ
> > - << MAX77686_OPMODE_BUCK234_SHIFT;
> > + break;
> > + case MAX77686_BUCK2 ... MAX77686_BUCK4:
> > + val = MAX77686_BUCK_OFF_PWRREQ << MAX77686_OPMODE_BUCK234_SHIFT;
> > + break;
> > + case MAX77686_LDO2:
> > + case MAX77686_LDO6 ... MAX77686_LDO8:
> > + case MAX77686_LDO10 ... MAX77686_LDO12:
> > + case MAX77686_LDO14 ... MAX77686_LDO16:
> > + val = MAX77686_LDO_OFF_PWRREQ << MAX77686_OPMODE_SHIFT;
> > + break;
> > + default:
> > + pr_warn("%s: regulator_suspend_disable not supported\n",
> > + rdev->desc->name);
> > + return -EINVAL;
> > + }
> >
> > ret = regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
> > rdev->desc->enable_mask, val);
> > @@ -176,13 +189,53 @@ static int max77686_ldo_set_suspend_mode(struct regulator_dev *rdev,
> > return 0;
> > }
> >
> > +/*
> > + * For regulators supporting disabled in suspend it checks if opmode
> > + * is 'off_pwrreq' mode (disabled in suspend) and changes it to 'enable'.
> > + * For other regulators does nothing.
> > + */
> > +static void max77686_set_opmode_enable(struct max77686_data *max77686, int id)
> > +{
> > + unsigned int opmode_shift;
> > +
> > + /*
> > + * Same enable function is used for LDO and bucks. Assuming
> > + * the same values are used for enable registers.
> > + */
> > + BUILD_BUG_ON(MAX77686_LDO_OFF_PWRREQ != MAX77686_BUCK_OFF_PWRREQ);
> > + BUILD_BUG_ON(MAX77686_LDO_NORMAL != MAX77686_BUCK_NORMAL);
> > +
> > + switch (id) {
> > + case MAX77686_BUCK1:
> > + opmode_shift = 0;
> > + break;
> > + case MAX77686_BUCK2 ... MAX77686_BUCK4:
> > + opmode_shift = MAX77686_OPMODE_BUCK234_SHIFT;
> > + break;
> > + case MAX77686_LDO2:
> > + case MAX77686_LDO6 ... MAX77686_LDO8:
> > + case MAX77686_LDO10 ... MAX77686_LDO12:
> > + case MAX77686_LDO14 ... MAX77686_LDO16:
> > + opmode_shift = MAX77686_OPMODE_SHIFT;
> > + break;
> > + default:
> > + return;
> > + }
> > +
> > + if (max77686->opmode[id] == (MAX77686_LDO_OFF_PWRREQ << opmode_shift))
> > + max77686->opmode[id] = MAX77686_LDO_NORMAL << opmode_shift;
> > +}
> > +
> > static int max77686_enable(struct regulator_dev *rdev)
> > {
> > struct max77686_data *max77686 = rdev_get_drvdata(rdev);
> > + int id = rdev_get_id(rdev);
> > +
> > + max77686_set_opmode_enable(max77686, id);
> >
> > return regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
> > rdev->desc->enable_mask,
> > - max77686->opmode[rdev_get_id(rdev)]);
> > + max77686->opmode[id]);
> > }
>
> the max77802 driver handles this slightly differently. It stores in opmode[id]
> just the value without the shift and there is a max77802_get_opmode_shift() to
> obtain the shift that is used before updating the register, e.g:
>
> int shift = max77802_get_opmode_shift(id);
> return regmap_update_bits(..., max77802->opmode[id] << shift);
>
> I think the max77802 driver approach is better since it avoids duplicating the
> switch statement to get the shift for each regulator. Just look how the max77802
> enable and disable functions are easier to read. Looking at the max77686 driver,
> I see that there are assumptions that opmode[id] has the value shifted so your
> changes are consistent with the rest of the driver but I would consider changing
> this.
Storing opmode in non-shifted form is intuitive also to me. That's way I
slipped the bug in previous version.
I'll change this to non-shifted opmode. The patch will grow bigger but
the code should be more readable.
Thanks!
Krzysztof
> Best regards,
> Javier
>
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