linux-kernel - Re: [PATCH v1 3/4] usb: dwc3: exynos: Use devm_regulator_bulk_get

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Date: Sat, 2 Mar 2024 22:18:39 +0530
From: Anand Moon <linux.amoon@...il.com>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc: Thinh Nguyen <Thinh.Nguyen@...opsys.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>, Alim Akhtar <alim.akhtar@...sung.com>, 
	linux-usb@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 3/4] usb: dwc3: exynos: Use devm_regulator_bulk_get_enable()
 helper function

Hi Christophe,

On Sat, 2 Mar 2024 at 21:20, Christophe JAILLET
<christophe.jaillet@...adoo.fr> wrote:
>
> Le 01/03/2024 à 20:38, Anand Moon a écrit :
> > Use devm_regulator_bulk_get_enable() instead of open coded
> > 'devm_regulator_get(), regulator_enable(), regulator_disable().
> >
> > Signed-off-by: Anand Moon <linux.amoon@...il.com>
> > ---
> >   drivers/usb/dwc3/dwc3-exynos.c | 49 +++-------------------------------
> >   1 file changed, 4 insertions(+), 45 deletions(-)
> >
> > diff --git a/drivers/usb/dwc3/dwc3-exynos.c b/drivers/usb/dwc3/dwc3-exynos.c
> > index 5d365ca51771..7c77f3c69825 100644
> > --- a/drivers/usb/dwc3/dwc3-exynos.c
> > +++ b/drivers/usb/dwc3/dwc3-exynos.c
> > @@ -32,9 +32,6 @@ struct dwc3_exynos {
> >       struct clk              *clks[DWC3_EXYNOS_MAX_CLOCKS];
> >       int                     num_clks;
> >       int                     suspend_clk_idx;
> > -
> > -     struct regulator        *vdd33;
> > -     struct regulator        *vdd10;
> >   };
> >
> >   static int dwc3_exynos_probe(struct platform_device *pdev)
> > @@ -44,6 +41,7 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
> >       struct device_node      *node = dev->of_node;
> >       const struct dwc3_exynos_driverdata *driver_data;
> >       int                     i, ret;
> > +     static const char * const regulators[] = { "vdd33", "vdd10" };
> >
> >       exynos = devm_kzalloc(dev, sizeof(*exynos), GFP_KERNEL);
> >       if (!exynos)
> > @@ -78,27 +76,9 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
> >       if (exynos->suspend_clk_idx >= 0)
> >               clk_prepare_enable(exynos->clks[exynos->suspend_clk_idx]);
> >
> > -     exynos->vdd33 = devm_regulator_get(dev, "vdd33");
> > -     if (IS_ERR(exynos->vdd33)) {
> > -             ret = PTR_ERR(exynos->vdd33);
> > -             goto vdd33_err;
> > -     }
> > -     ret = regulator_enable(exynos->vdd33);
> > -     if (ret) {
> > -             dev_err(dev, "Failed to enable VDD33 supply\n");
> > -             goto vdd33_err;
> > -     }
> > -
> > -     exynos->vdd10 = devm_regulator_get(dev, "vdd10");
> > -     if (IS_ERR(exynos->vdd10)) {
> > -             ret = PTR_ERR(exynos->vdd10);
> > -             goto vdd10_err;
> > -     }
> > -     ret = regulator_enable(exynos->vdd10);
> > -     if (ret) {
> > -             dev_err(dev, "Failed to enable VDD10 supply\n");
> > -             goto vdd10_err;
> > -     }
> > +     ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(regulators), regulators);
> > +     if (ret)
> > +             return dev_err_probe(dev, ret, "Failed to enable regulators\n");
> >
> >       if (node) {
> >               ret = of_platform_populate(node, NULL, NULL, dev);
> > @@ -115,10 +95,6 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
> >       return 0;
> >
> >   populate_err:
> > -     regulator_disable(exynos->vdd10);
> > -vdd10_err:
> > -     regulator_disable(exynos->vdd33);
> > -vdd33_err:
> >       for (i = exynos->num_clks - 1; i >= 0; i--)
> >               clk_disable_unprepare(exynos->clks[i]);
> >
> > @@ -140,9 +116,6 @@ static void dwc3_exynos_remove(struct platform_device *pdev)
> >
> >       if (exynos->suspend_clk_idx >= 0)
> >               clk_disable_unprepare(exynos->clks[exynos->suspend_clk_idx]);
> > -
> > -     regulator_disable(exynos->vdd33);
> > -     regulator_disable(exynos->vdd10);
> >   }
> >
> >   static const struct dwc3_exynos_driverdata exynos5250_drvdata = {
> > @@ -196,9 +169,6 @@ static int dwc3_exynos_suspend(struct device *dev)
> >       for (i = exynos->num_clks - 1; i >= 0; i--)
> >               clk_disable_unprepare(exynos->clks[i]);
> >
> > -     regulator_disable(exynos->vdd33);
> > -     regulator_disable(exynos->vdd10);
>
> Hi,
>
> Same here, I don't think that removing regulator_[en|dis]able from the
> suspend and resume function is correct.
>
> The goal is to stop some hardware when the system is suspended, in order
> to save some power.
Ok,
>
> Why did you removed it?

As per the description of the function  devm_regulator_bulk_get_enable

* This helper function allows drivers to get several regulator
 * consumers in one operation with management, the regulators will
 * automatically be freed when the device is unbound.  If any of the
 * regulators cannot be acquired then any regulators that were
 * allocated will be freed before returning to the caller.

[0] https://elixir.bootlin.com/linux/latest/source/drivers/regulator/devresc#L330

I have tested with rtc suspend resume and did not find any issue with
this.patch.

>
> CJ
>
Thanks
-Anand