linux-kernel - RE: [PATCH v14 10/17] PCI: imx6: Turn off regulator when system is in suspend mode

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Date:   Wed, 13 Jul 2022 10:56:39 +0000
From:   Hongxing Zhu <hongxing.zhu@....com>
To:     Lucas Stach <l.stach@...gutronix.de>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "festevam@...il.com" <festevam@...il.com>,
        "francesco.dolcini@...adex.com" <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>
Subject: RE: [PATCH v14 10/17] PCI: imx6: Turn off regulator when system is in
 suspend mode


> -----Original Message-----
> From: Lucas Stach <l.stach@...gutronix.de>
> Sent: 2022年7月13日 16:34
> To: Hongxing Zhu <hongxing.zhu@....com>; bhelgaas@...gle.com;
> robh+dt@...nel.org; broonie@...nel.org; lorenzo.pieralisi@....com;
> festevam@...il.com; 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>
> Subject: Re: [PATCH v14 10/17] PCI: imx6: Turn off regulator when system is in
> suspend mode
> 
> Am Freitag, dem 01.07.2022 um 11:25 +0800 schrieb Richard Zhu:
> > 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%7C361c9bf365b64895482808da6
> 4aa7cca%
> >
> 7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6379329806385373
> 39%7CUnkn
> >
> own%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1
> haWwi
> >
> LCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=A%2Fw6AFCddC0T%2FA
> ocBT%2F7OJZ
> > ddAeYPTbgeAxpHpPubkw%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 2b42c37f1617..f72eb609769b 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;
> >
> > -	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",
> 
> The regulator really has nothing to do with the core reset. Please move this
> regulator enable into imx6_pcie_host_init().
Hi Lucas:
Thanks for your comments.
Got that. Had done it in the 11/17 commit.

> 
> > @@ -795,7 +785,7 @@ 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", @@
> -1022,6
> > +1012,9 @@ static int imx6_pcie_suspend_noirq(struct device *dev)
> >  		break;
> >  	}
> >
> > +	if (imx6_pcie->vpcie)
> > +		regulator_disable(imx6_pcie->vpcie);
> > +
> >  	return 0;
> >  }
> >
> > @@ -1268,6 +1261,8 @@ 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);
> 
> This looks like a separate change, not mentioned in the commit message.
> I'm not sure if we should do this. Shutdown is supposed to just stop the device,
> which is already achieved by imx6_pcie_assert_core_reset().
> 
> If we would want to do a full cleanup here we would also need to disable
> clocks and get the reset GPIO into asserted state. I don't think we want to do
> all of this here.
The regulator_disable() was contained in imx6_pcie_assert_core_reset() before.
When refine the regulator usage, the regulator_disable() is moved out of
 imx6_pcie_assert_core_reset().
Based on the discussion [1] with Francesco.
To keep the same behavior, the regulator_disable() is placed behind of
 imx6_pcie_assert_core_reset() in imx6_pcie_shutdown() here.
[1]https://patchwork.ozlabs.org/project/linux-pci/patch/1644290735-3797-6-git-send-email-hongxing.zhu@nxp.com/

Best Regards
Richard

> 
> Regards,
> Lucas
> >  }
> >
> >  static const struct imx6_pcie_drvdata drvdata[] = {
>