linux-kernel - RE: [PATCH 1/3] usb: ohci-exynos: Make provision for vdd regulators

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Date:	Thu, 24 Apr 2014 09:38:04 +0900
From:	Anton Tikhomirov <av.tikhomirov@...sung.com>
To:	'Vivek Gautam' <gautam.vivek@...sung.com>,
	linux-usb@...r.kernel.org, linux-samsung-soc@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, gregkh@...uxfoundation.org,
	stern@...land.harvard.edu, balbi@...com, kgene.kim@...sung.com,
	'Jingoo Han' <jg1.han@...sung.com>
Subject: RE: [PATCH 1/3] usb: ohci-exynos: Make provision for vdd regulators

Hi,

> Hi,
> 
> > -----Original Message-----
> > From: linux-usb-owner@...r.kernel.org [mailto:linux-usb-
> > owner@...r.kernel.org] On Behalf Of Vivek Gautam
> > Sent: Monday, April 21, 2014 9:17 PM
> >
> > Facilitate getting required 3.3V and 1.0V VDD supply for
> > OHCI controller on Exynos.
> >
> > With patches for regulators' nodes merged in 3.15:
> > c8c253f ARM: dts: Add regulator entries to smdk5420
> > 275dcd2 ARM: dts: add max77686 pmic node for smdk5250,
> >
> > certain perripherals will now need to ensure that,
> > they request VDD regulators in their drivers, and enable
> > them so as to make them working.
> >
> > Signed-off-by: Vivek Gautam <gautam.vivek@...sung.com>
> > Cc: Jingoo Han <jg1.han@...sung.com>
> > ---
> >
> > Based on 'usb-next' branch of Greg's usb tree.
> >
> >  drivers/usb/host/ohci-exynos.c |   47
> > ++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 47 insertions(+)
> >
> > diff --git a/drivers/usb/host/ohci-exynos.c b/drivers/usb/host/ohci-
> > exynos.c
> > index 68588d8..e2e72a8 100644
> > --- a/drivers/usb/host/ohci-exynos.c
> > +++ b/drivers/usb/host/ohci-exynos.c
> > @@ -18,6 +18,7 @@
> >  #include <linux/module.h>
> >  #include <linux/of.h>
> >  #include <linux/platform_device.h>
> > +#include <linux/regulator/consumer.h>
> >  #include <linux/usb/phy.h>
> >  #include <linux/usb/samsung_usb_phy.h>
> >  #include <linux/usb.h>
> > @@ -37,6 +38,8 @@ struct exynos_ohci_hcd {
> >  	struct clk *clk;
> >  	struct usb_phy *phy;
> >  	struct usb_otg *otg;
> > +	struct regulator *vdd33;
> > +	struct regulator *vdd10;
> >  };
> >
> >  static void exynos_ohci_phy_enable(struct platform_device *pdev)
> > @@ -98,6 +101,28 @@ static int exynos_ohci_probe(struct
> platform_device
> > *pdev)
> >  		exynos_ohci->otg = phy->otg;
> >  	}
> >
> > +	exynos_ohci->vdd33 = devm_regulator_get(&pdev->dev, "vdd33");
> > +	if (IS_ERR(exynos_ohci->vdd33)) {
> > +		err = PTR_ERR(exynos_ohci->vdd33);
> > +		goto fail_regulator1;
> > +	}
> > +	err = regulator_enable(exynos_ohci->vdd33);
> > +	if (err) {
> > +		dev_err(&pdev->dev, "Failed to enable VDD33 supply\n");
> > +		goto fail_regulator1;
> > +	}
> > +
> > +	exynos_ohci->vdd10 = devm_regulator_get(&pdev->dev, "vdd10");
> > +	if (IS_ERR(exynos_ohci->vdd10)) {
> > +		err = PTR_ERR(exynos_ohci->vdd10);
> > +		goto fail_regulator2;
> > +	}
> > +	err = regulator_enable(exynos_ohci->vdd10);
> > +	if (err) {
> > +		dev_err(&pdev->dev, "Failed to enable VDD10 supply\n");
> > +		goto fail_regulator2;
> > +	}
> > +
> 
> Do we need to skip regulator settings together with PHY configuration
> in case of exynos5440?
> 
> >  skip_phy:
> >  	exynos_ohci->clk = devm_clk_get(&pdev->dev, "usbhost");
> >
> > @@ -154,6 +179,10 @@ fail_add_hcd:
> >  fail_io:
> >  	clk_disable_unprepare(exynos_ohci->clk);
> >  fail_clk:
> > +	regulator_disable(exynos_ohci->vdd10);
> > +fail_regulator2:
> > +	regulator_disable(exynos_ohci->vdd33);
> > +fail_regulator1:
> >  	usb_put_hcd(hcd);
> >  	return err;
> >  }
> > @@ -172,6 +201,9 @@ static int exynos_ohci_remove(struct
> > platform_device *pdev)
> >
> >  	clk_disable_unprepare(exynos_ohci->clk);
> >
> > +	regulator_disable(exynos_ohci->vdd10);
> > +	regulator_disable(exynos_ohci->vdd33);
> > +
> >  	usb_put_hcd(hcd);
> >
> >  	return 0;
> > @@ -208,6 +240,9 @@ static int exynos_ohci_suspend(struct device *dev)
> >
> >  	clk_disable_unprepare(exynos_ohci->clk);
> >
> > +	regulator_disable(exynos_ohci->vdd10);
> > +	regulator_disable(exynos_ohci->vdd33);
> > +
> >  	spin_unlock_irqrestore(&ohci->lock, flags);
> >
> >  	return 0;
> > @@ -218,6 +253,18 @@ static int exynos_ohci_resume(struct device *dev)
> >  	struct usb_hcd *hcd			= dev_get_drvdata(dev);
> >  	struct exynos_ohci_hcd *exynos_ohci	= to_exynos_ohci(hcd);
> >  	struct platform_device *pdev		= to_platform_device(dev);
> > +	int ret;
> > +
> > +	ret = regulator_enable(exynos_ohci->vdd33);
> > +	if (ret) {
> > +		dev_err(dev, "Failed to enable VDD33 supply\n");
> > +		return ret;
> 
> Not sure, but shall we continue resuming and do everything
> we can in case of error? At least it will avoid
> WARN_ON(clk->enable_count == 0) on next system suspend.

On the other hand, if power is not applied to the controller,
register access in ohci_resume() may lead to undefined behavior.
What's your opinion?

> 
> > +	}
> > +	ret = regulator_enable(exynos_ohci->vdd10);
> > +	if (ret) {
> > +		dev_err(dev, "Failed to enable VDD10 supply\n");
> > +		return ret;
> > +	}
> >
> >  	clk_prepare_enable(exynos_ohci->clk);
> >
> > --
> 
> Thanks

Thanks

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