linux-kernel - Re: [PATCH 4/5] phy: tegra: xusb: Add support for power supplies

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Date:   Mon, 28 Jan 2019 09:00:54 +0100
From:   Thierry Reding <thierry.reding@...il.com>
To:     jckuo <jckuo@...dia.com>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] phy: tegra: xusb: Add support for power supplies

On Mon, Jan 28, 2019 at 03:22:09PM +0800, jckuo wrote:
> Hi Thierry,
> 
> I think any non-zero return value of
> regulator_bulk_enable()/devm_regulator_bulk_get() means error.
> 
> Thanks,
> 
> JC

Theoretically I think only regulator_bulk_enable() could return a
positive value, but even so it never will in practice because all of the
regulator_enable() (see _regulator_enable()) calls will only ever return
negative error codes.

I can change this and resend if you have strong concerns about this
possibly missing legitimate error cases.

Thierry

> On 1/25/19 7:25 PM, Thierry Reding wrote:
> > From: Thierry Reding <treding@...dia.com>
> > 
> > Support enabling various supplies needed to provide power to the PLLs
> > and logic used to drive the USB, PCI and SATA pads.
> > 
> > Signed-off-by: Thierry Reding <treding@...dia.com>
> > ---
> >   drivers/phy/tegra/xusb.c | 34 +++++++++++++++++++++++++++++++++-
> >   drivers/phy/tegra/xusb.h |  5 +++++
> >   2 files changed, 38 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/phy/tegra/xusb.c b/drivers/phy/tegra/xusb.c
> > index 57a2d08ef6da..e510629f4f1c 100644
> > --- a/drivers/phy/tegra/xusb.c
> > +++ b/drivers/phy/tegra/xusb.c
> > @@ -864,6 +864,7 @@ static int tegra_xusb_padctl_probe(struct platform_device *pdev)
> >   	struct tegra_xusb_padctl *padctl;
> >   	const struct of_device_id *match;
> >   	struct resource *res;
> > +	unsigned int i;
> >   	int err;
> >   	/* for backwards compatibility with old device trees */
> > @@ -901,14 +902,38 @@ static int tegra_xusb_padctl_probe(struct platform_device *pdev)
> >   		goto remove;
> >   	}
> > +	padctl->supplies = devm_kcalloc(&pdev->dev, padctl->soc->num_supplies,
> > +					sizeof(*padctl->supplies), GFP_KERNEL);
> > +	if (!padctl->supplies) {
> > +		err = -ENOMEM;
> > +		goto remove;
> > +	}
> > +
> > +	for (i = 0; i < padctl->soc->num_supplies; i++)
> > +		padctl->supplies[i].supply = padctl->soc->supply_names[i];
> > +
> > +	err = devm_regulator_bulk_get(&pdev->dev, padctl->soc->num_supplies,
> > +				      padctl->supplies);
> > +	if (err < 0) {
> > +		dev_err(&pdev->dev, "failed to get regulators: %d\n", err);
> > +		goto remove;
> > +	}
> > +
> >   	err = reset_control_deassert(padctl->rst);
> >   	if (err < 0)
> >   		goto remove;
> > +	err = regulator_bulk_enable(padctl->soc->num_supplies,
> > +				    padctl->supplies);
> > +	if (err < 0) {
> > +		dev_err(&pdev->dev, "failed to enable supplies: %d\n", err);
> > +		goto reset;
> > +	}
> > +
> >   	err = tegra_xusb_setup_pads(padctl);
> >   	if (err < 0) {
> >   		dev_err(&pdev->dev, "failed to setup pads: %d\n", err);
> > -		goto reset;
> > +		goto power_down;
> >   	}
> >   	err = tegra_xusb_setup_ports(padctl);
> > @@ -921,6 +946,8 @@ static int tegra_xusb_padctl_probe(struct platform_device *pdev)
> >   remove_pads:
> >   	tegra_xusb_remove_pads(padctl);
> > +power_down:
> > +	regulator_bulk_disable(padctl->soc->num_supplies, padctl->supplies);
> >   reset:
> >   	reset_control_assert(padctl->rst);
> >   remove:
> > @@ -936,6 +963,11 @@ static int tegra_xusb_padctl_remove(struct platform_device *pdev)
> >   	tegra_xusb_remove_ports(padctl);
> >   	tegra_xusb_remove_pads(padctl);
> > +	err = regulator_bulk_disable(padctl->soc->num_supplies,
> > +				     padctl->supplies);
> > +	if (err < 0)
> > +		dev_err(&pdev->dev, "failed to disable supplies: %d\n", err);
> > +
> >   	err = reset_control_assert(padctl->rst);
> >   	if (err < 0)
> >   		dev_err(&pdev->dev, "failed to assert reset: %d\n", err);
> > diff --git a/drivers/phy/tegra/xusb.h b/drivers/phy/tegra/xusb.h
> > index bb60fc09c752..5d5d22f6cb41 100644
> > --- a/drivers/phy/tegra/xusb.h
> > +++ b/drivers/phy/tegra/xusb.h
> > @@ -370,6 +370,9 @@ struct tegra_xusb_padctl_soc {
> >   	} ports;
> >   	const struct tegra_xusb_padctl_ops *ops;
> > +
> > +	const char * const *supply_names;
> > +	unsigned int num_supplies;
> >   };
> >   struct tegra_xusb_padctl {
> > @@ -393,6 +396,8 @@ struct tegra_xusb_padctl {
> >   	unsigned int enable;
> >   	struct clk *clk;
> > +
> > +	struct regulator_bulk_data *supplies;
> >   };
> >   static inline void padctl_writel(struct tegra_xusb_padctl *padctl, u32 value,

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