Re: [PATCH v8 5/8] PCI: imx6: Refine the regulator usage

Francesco Dolcini
2022-02-25T09:43:11Z

On Fri, Feb 25, 2022 at 11:44:24AM +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().
>
> To keep the balance of the regulator usage counter, disable the regulator
> just behind of imx6_pcie_assert_core_reset() in resume and shutdown.

While this patch does not look wrong and improving the existing code, I
do have a couple of concern.

1. It's weird that regulator enable/disable are really non symmetric in
the code, enable is in imx6_pcie_deassert_core_reset(), while disable is
not in imx6_pcie_assert_core_reset() but spread around.

2. We are playing around with vpcie during regulator during
suspend/resume, why? We currently have issue with suspend/resume when a
PCIe switch is there, with the final effect of PCIe being not usable
afterward. I fear like this is related to our issue.

What about vpcie enable in probe, and vpcie disable in shutdown and
that's all?

Francesco

>
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.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 0f1b8c873a4a..160a0bd02098 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -369,8 +369,6 @@ static int imx6_pcie_attach_pd(struct device *dev)
>
> 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:
> @@ -400,14 +398,6 @@ static void imx6_pcie_assert_core_reset(struct imx6_pcie *imx6_pcie)
> IMX6Q_GPR1_PCIE_REF_CLK_EN, 0 << 16);
> 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);
> - }
> }
>
> static unsigned int imx6_pcie_grp_offset(const struct imx6_pcie *imx6_pcie)
> @@ -584,7 +574,7 @@ 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",
> @@ -657,7 +647,7 @@ 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",
> @@ -1029,6 +1019,9 @@ static int imx6_pcie_resume_noirq(struct device *dev)
> return 0;
>
> imx6_pcie_assert_core_reset(imx6_pcie);
> + if (imx6_pcie->vpcie)
> + regulator_disable(imx6_pcie->vpcie);
> +
> imx6_pcie_init_phy(imx6_pcie);
> imx6_pcie_deassert_core_reset(imx6_pcie);
> dw_pcie_setup_rc(pp);
> @@ -1262,6 +1255,8 @@ 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
>