Re: [PATCH v13 10/15] PCI: imx6: Turn off regulator when system is in suspend mode

From: Bjorn Helgaas
Date: Thu Jun 23 2022 - 18:19:51 EST


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://lore.kernel.org/r/1655189942-12678-6-git-send-email-hongxing.z
> 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.

Bjorn