linux-kernel - RE: [PATCH v12 09/13] PCI: imx6: Turn off regulator when system is in suspend mode

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Date:   Thu, 16 Jun 2022 02:23:29 +0000
From:   Hongxing Zhu <hongxing.zhu@....com>
To:     Bjorn Helgaas <helgaas@...nel.org>,
        Lucas Stach <l.stach@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Fabio Estevam <festevam@...il.com>,
        Francesco Dolcini <francesco.dolcini@...adex.com>
CC:     "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        dl-linux-imx <linux-imx@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: RE: [PATCH v12 09/13] PCI: imx6: Turn off regulator when system is in
 suspend mode

> -----Original Message-----
> From: Bjorn Helgaas <helgaas@...nel.org>
> Sent: 2022年6月16日 7:31
> To: Hongxing Zhu <hongxing.zhu@....com>; Lucas Stach
> <l.stach@...gutronix.de>; Rob Herring <robh+dt@...nel.org>; Mark Brown
> <broonie@...nel.org>; Lorenzo Pieralisi <lorenzo.pieralisi@....com>; Fabio
> Estevam <festevam@...il.com>; Francesco Dolcini
> <francesco.dolcini@...adex.com>
> Cc: linux-pci@...r.kernel.org; linux-arm-kernel@...ts.infradead.org;
> linux-kernel@...r.kernel.org; kernel@...gutronix.de; dl-linux-imx
> <linux-imx@....com>; Bjorn Helgaas <bhelgaas@...gle.com>
> Subject: Re: [PATCH v12 09/13] PCI: imx6: Turn off regulator when system is in
> suspend mode
> 
> On Wed, Jun 15, 2022 at 06:15:47PM -0500, Bjorn Helgaas wrote:
> > From: Richard Zhu <hongxing.zhu@....com>
> >
> > The driver should undo any enables it did itself. The regulator
> > disable shouldn't be basing decisions on regulator_is_enabled().
> >
> > Move the regulator_disable to the suspend function, turn off regulator
> > when the system is in suspend mode.
> >
> > To keep the balance of the regulator usage counter, disable the
> > regulator in shutdown.
> >
> > Link:
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore
> > .kernel.org%2Fr%2F1655189942-12678-6-git-send-email-hongxing.z&amp;d
> at
> >
> a=05%7C01%7Chongxing.zhu%40nxp.com%7C8dea46d908d34cb4825808da4
> f270eaf%
> >
> 7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6379093264156415
> 35%7CUnkn
> >
> own%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1
> haWwi
> >
> LCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=tqzlcCmtSkUNxNzJ0Fr5o
> CR3X2CTH
> > 4dwUJS4NXt5KRc%3D&amp;reserved=0
> > hu@....com
> > Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> > Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> > ---
> >  drivers/pci/controller/dwc/pci-imx6.c | 19 +++++++------------
> >  1 file changed, 7 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index 6eddd0b5f628..537b8a2e0e3b 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -670,8 +670,6 @@ static void imx6_pcie_clk_disable(struct imx6_pcie
> > *imx6_pcie)
> >
> >  static void imx6_pcie_assert_core_reset(struct imx6_pcie *imx6_pcie)
> > {
> > -	struct device *dev = imx6_pcie->pci->dev;
> > -
> >  	switch (imx6_pcie->drvdata->variant) {
> >  	case IMX7D:
> >  	case IMX8MQ:
> > @@ -702,14 +700,6 @@ static void imx6_pcie_assert_core_reset(struct
> imx6_pcie *imx6_pcie)
> >  		break;
> >  	}
> >
> > -	if (imx6_pcie->vpcie && regulator_is_enabled(imx6_pcie->vpcie) > 0) {
> > -		int ret = regulator_disable(imx6_pcie->vpcie);
> > -
> > -		if (ret)
> > -			dev_err(dev, "failed to disable vpcie regulator: %d\n",
> > -				ret);
> > -	}
> > -
> >  	/* Some boards don't have PCIe reset GPIO. */
> >  	if (gpio_is_valid(imx6_pcie->reset_gpio))
> >  		gpio_set_value_cansleep(imx6_pcie->reset_gpio,
> > @@ -722,7 +712,7 @@ static int imx6_pcie_deassert_core_reset(struct
> imx6_pcie *imx6_pcie)
> >  	struct device *dev = pci->dev;
> >  	int ret, err;
> >
> > -	if (imx6_pcie->vpcie && !regulator_is_enabled(imx6_pcie->vpcie)) {
> > +	if (imx6_pcie->vpcie) {
> >  		ret = regulator_enable(imx6_pcie->vpcie);
> >  		if (ret) {
> >  			dev_err(dev, "failed to enable vpcie regulator: %d\n", @@
> -796,7
> > +786,7 @@ static int imx6_pcie_deassert_core_reset(struct imx6_pcie
> *imx6_pcie)
> >  	return 0;
> >
> >  err_clks:
> > -	if (imx6_pcie->vpcie && regulator_is_enabled(imx6_pcie->vpcie) > 0) {
> > +	if (imx6_pcie->vpcie) {
> >  		ret = regulator_disable(imx6_pcie->vpcie);
> >  		if (ret)
> >  			dev_err(dev, "failed to disable vpcie regulator: %d\n", @@
> -1023,6
> > +1013,9 @@ static int imx6_pcie_suspend_noirq(struct device *dev)
> >  		break;
> >  	}
> >
> > +	if (imx6_pcie->vpcie)
> > +		regulator_disable(imx6_pcie->vpcie);
> 
> This is a little bit ugly because imx6_pcie_suspend_noirq() and
> imx6_pcie_resume_noirq() are not symmetric.
> 
> We call regulator_disable() directly here in imx6_pcie_suspend_noirq(), but the
> corresponding regulator_enable() is buried in imx6_pcie_deassert_core_reset().
> 
> It would be nicer if the suspend and resume paths looked more similar, as
> rockchip_pcie_suspend_noirq() and rockchip_pcie_resume_noirq() do, for
> example.
Yes, it is. The regulator_disable()/regulator_enable() are not invoked
 symmetrically.

In the original codes, the regulator_disable() is contained in
imx6_pcie_assert_core_reset() and with _eanbled() check.
And regulator_enable() is embedded in imx6_pcie_deassert_core_reset().
Both the regulator disable and enable are invoked in resume before.
I move the regulator_disable to suspend mode refer to Lucas' comments.

Refer to the current situation, how about to move the regulator_disable()
 out of imx6_pcie_deassert_core_reset() too?

Best Regards
Richard Zhu

> 
> >  	return 0;
> >  }
> >
> > @@ -1269,6 +1262,8 @@ static void imx6_pcie_shutdown(struct
> > platform_device *pdev)
> >
> >  	/* bring down link, so bootloader gets clean state in case of reboot */
> >  	imx6_pcie_assert_core_reset(imx6_pcie);
> > +	if (imx6_pcie->vpcie)
> > +		regulator_disable(imx6_pcie->vpcie);
> >  }
> >
> >  static const struct imx6_pcie_drvdata drvdata[] = {
> > --
> > 2.25.1
> >
> >
> > _______________________________________________
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> nown%7CTW
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> FpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXV
> CI6
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> > hcieKs%2BKqg%3D&amp;reserved=0