> -----Original Message----- > From: Bjorn Helgaas <helgaas@xxxxxxxxxx> > Sent: 2022年6月28日 3:52 > To: Hongxing Zhu <hongxing.zhu@xxxxxxx> > Cc: l.stach@xxxxxxxxxxxxxx; bhelgaas@xxxxxxxxxx; robh+dt@xxxxxxxxxx; > broonie@xxxxxxxxxx; lorenzo.pieralisi@xxxxxxx; festevam@xxxxxxxxx; > francesco.dolcini@xxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > kernel@xxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx> > Subject: Re: [PATCH v13 10/15] PCI: imx6: Turn off regulator when system is in > suspend mode > > On Fri, Jun 24, 2022 at 05:05:00AM +0000, Hongxing Zhu wrote: > > > -----Original Message----- > > > From: Bjorn Helgaas <helgaas@xxxxxxxxxx> > > > Sent: 2022年6月24日 6:20 > > > To: Hongxing Zhu <hongxing.zhu@xxxxxxx> > > > Cc: l.stach@xxxxxxxxxxxxxx; bhelgaas@xxxxxxxxxx; robh+dt@xxxxxxxxxx; > > > broonie@xxxxxxxxxx; lorenzo.pieralisi@xxxxxxx; festevam@xxxxxxxxx; > > > francesco.dolcini@xxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; > > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > > > kernel@xxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx> > > > Subject: Re: [PATCH v13 10/15] PCI: imx6: Turn off regulator when > > > system is in suspend mode > > > > > > On Fri, Jun 17, 2022 at 06:31:09PM +0800, Richard Zhu wrote: > > > > 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%2F > > > > lore > > > > .kernel.org%2Fr%2F1655189942-12678-6-git-send-email-hongxing.z&am > p > > > > ;d > > > at > > > > > > > > a=05%7C01%7Chongxing.zhu%40nxp.com%7C5633fa1bf3c443e203e108da55 > > > 667dc2% > > > > > > > > 7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6379161959277276 > > > 04%7CUnkn > > > > > > > > own%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1 > > > haWwi > > > > > > > > LCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=1Kbzn3XSVvt3gGPrEy%2 > > > BET8EZn4I > > > > dwS%2BhUZ3AalZ2YZ0%3D&reserved=0 > > > > hu@xxxxxxx > > > > Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx> > > > > Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > > > > --- > > > > 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", @@ > > > -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; > > > > } > > > > > > The suspend and resume methods should be symmetric, and they should > > > *look* symmetric. > > > > > > imx6_pcie_suspend_noirq() disables the regulator, so > > > imx6_pcie_resume_noirq() should enable it. > > > > > > imx6_pcie_suspend_noirq() calls imx6_pcie_clk_disable() to disable > > > several clocks. imx6_pcie_resume_noirq() should call > > > imx6_pcie_clk_enable() to enable them. > > > > > > imx6_pcie_clk_enable() *is* called in the resume path, but it's > > > buried inside imx6_pcie_host_init() and > > > imx6_pcie_deassert_core_reset(). That makes it hard to analyze. > > > > > > We should be able to look at imx6_pcie_suspend_noirq() and > > > imx6_pcie_resume_noirq() and easily see that the resume path resumes > > > everything that was suspended in the suspend path. > > > > Yes, it is. It's better to keep suspend/resume symmetric as much as > > possible. In resume, the host_init is invoked, clocks, regulators and > > so on would be initialized properly. > > > > Unfortunately, there is no according host_exit() that can be called to > > do the reversed clocks, regulators disable operations in the suspend. > > So, the clocks and regulator disable are explicitly invoked in suspend > > callback. > > > > How about to do the incremental updates if the .host_exit can be added > > later? > > This doesn't seem very convincing because everything here is in the > imx6 domain. The only DWC core thing here is the dw_pcie_setup_rc() called > in imx6_pcie_resume_noirq(), and it doesn't call back to any > imx6 code. > > So you should be able to make an imx6_pcie_host_exit() or whatever that > corresponds to imx6_pcie_host_init(). Hi Bjorn: Thanks for your kindly help to review it. That's reasonable. So, to make it symmetric with imx6_pcie_host_init() and imx6_pcie_start_link(). The according local functions imx6_pcie_host_exit() and imx6_pcie_stop_link() would be created. BTW, to be symmetric with imx6_pcie_host_init(), the parameter of imx6_pcie_host_exit() is same to the parameter of imx6_pcie_host_init(). So do imx6_pcie_stop_link() and imx6_pcie_start_link(). Are you satisfied with the following functions? static void imx6_pcie_stop_link(struct dw_pcie *pci) { struct device *dev = pci->dev; /* Turn off PCIe LTSSM */ imx6_pcie_ltssm_disable(dev); } static void imx6_pcie_host_exit(struct pcie_port *pp) { struct dw_pcie *pci = to_dw_pcie_from_pp(pp); struct imx6_pcie *imx6_pcie = to_imx6_pcie(pci); imx6_pcie_clk_disable(imx6_pcie); if (imx6_pcie->phy) { if (phy_power_off(imx6_pcie->phy)) dev_err(pci->dev, "unable to power off PHY\n"); phy_exit(imx6_pcie->phy); } if (imx6_pcie->vpcie) regulator_disable(imx6_pcie->vpcie); } Best Regards Richard Zhu
