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    SubjectRe: [PATCH v2] PCI: imx: Add imx6sx suspend/resume support
    On Wed, Nov 7, 2018 at 5:57 AM Leonard Crestez <leonard.crestez@nxp.com> wrote:
    >
    > Enable PCI suspend/resume support on imx6sx socs. This is similar to
    > imx7d with a few differences:
    >
    > * The PM_Turn_Off bit is exposed through an IOMUX GPR, like all other
    > pcie control bits on 6sx.
    > * The pcie_inbound_axi clk needs to be turned off in suspend. On resume
    > it is restored via resume -> deassert_core_reset -> enable_ref_clk.
    >
    > Most of the resume logic is shared with the initial reset after probe.
    >
    > Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
    >
    > ---
    > Changes since v1:
    > * Use a switch statement in imx6_pcie_pm_turnoff. The DT-based turnoff
    > path is still an if statement.
    > * Did not split imx6_pcie_clk_disable or call it from other paths, this
    > would bring complications and is somewhat unrelated.
    > * See v1 comments: https://lore.kernel.org/patchwork/patch/996806/
    >
    > drivers/pci/controller/dwc/pci-imx6.c | 44 ++++++++++++++++++---
    > include/linux/mfd/syscon/imx6q-iomuxc-gpr.h | 1 +
    > 2 files changed, 40 insertions(+), 5 deletions(-)
    >
    > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
    > index 2cbef2d7c207..54625569d0bc 100644
    > --- a/drivers/pci/controller/dwc/pci-imx6.c
    > +++ b/drivers/pci/controller/dwc/pci-imx6.c
    > @@ -771,41 +771,75 @@ static void imx6_pcie_ltssm_disable(struct device *dev)
    > }
    > }
    >
    > static void imx6_pcie_pm_turnoff(struct imx6_pcie *imx6_pcie)
    > {
    > - reset_control_assert(imx6_pcie->turnoff_reset);
    > - reset_control_deassert(imx6_pcie->turnoff_reset);
    > + struct device *dev = imx6_pcie->pci->dev;
    > +
    > + /* Some variants have a turnoff reset in DT */
    > + if (imx6_pcie->turnoff_reset) {
    > + reset_control_assert(imx6_pcie->turnoff_reset);
    > + reset_control_deassert(imx6_pcie->turnoff_reset);
    > + goto pm_turnoff_sleep;
    > + }
    > +
    > + /* Others poke directly at IOMUXC registers */
    > + switch (imx6_pcie->variant) {
    > + case IMX6SX:
    > + regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
    > + IMX6SX_GPR12_PCIE_PM_TURN_OFF,
    > + IMX6SX_GPR12_PCIE_PM_TURN_OFF);
    > + regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
    > + IMX6SX_GPR12_PCIE_PM_TURN_OFF, 0);
    > + break;
    > + default:
    > + dev_err(dev, "PME_Turn_Off not implemented\n");
    > + return;

    Purely optionally, if you feel like avoiding goto you can change this to:

    default:
    if (!imx6_pcie->turnoff_reset) {
    dev_err(dev, "PME_Turn_Off not implemented\n");
    return;
    }

    reset_control_assert(imx6_pcie->turnoff_reset);
    reset_control_deassert(imx6_pcie->turnoff_reset);
    break;

    but that's up to you. FWIW, patch looks reasonable:

    Reviewed-by: Andrey Smirnov <andrew.smirnov@gmail.com>

    > + }
    >
    > /*
    > * Components with an upstream port must respond to
    > * PME_Turn_Off with PME_TO_Ack but we can't check.
    > *
    > * The standard recommends a 1-10ms timeout after which to
    > * proceed anyway as if acks were received.
    > */
    > +pm_turnoff_sleep:
    > usleep_range(1000, 10000);
    > }
    >
    > static void imx6_pcie_clk_disable(struct imx6_pcie *imx6_pcie)
    > {
    > clk_disable_unprepare(imx6_pcie->pcie);
    > clk_disable_unprepare(imx6_pcie->pcie_phy);
    > clk_disable_unprepare(imx6_pcie->pcie_bus);
    >
    > - if (imx6_pcie->variant == IMX7D) {
    > + switch (imx6_pcie->variant) {
    > + case IMX6SX:
    > + clk_disable_unprepare(imx6_pcie->pcie_inbound_axi);
    > + break;
    > + case IMX7D:
    > regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
    > IMX7D_GPR12_PCIE_PHY_REFCLK_SEL,
    > IMX7D_GPR12_PCIE_PHY_REFCLK_SEL);
    > + break;
    > + default:
    > + break;
    > }
    > }
    >
    > +static inline bool imx6_pcie_supports_suspend(struct imx6_pcie *imx6_pcie)
    > +{
    > + return (imx6_pcie->variant == IMX7D ||
    > + imx6_pcie->variant == IMX6SX);
    > +}
    > +
    > static int imx6_pcie_suspend_noirq(struct device *dev)
    > {
    > struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
    >
    > - if (imx6_pcie->variant != IMX7D)
    > + if (!imx6_pcie_supports_suspend(imx6_pcie))
    > return 0;
    >
    > imx6_pcie_pm_turnoff(imx6_pcie);
    > imx6_pcie_clk_disable(imx6_pcie);
    > imx6_pcie_ltssm_disable(dev);
    > @@ -817,11 +851,11 @@ static int imx6_pcie_resume_noirq(struct device *dev)
    > {
    > int ret;
    > struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
    > struct pcie_port *pp = &imx6_pcie->pci->pp;
    >
    > - if (imx6_pcie->variant != IMX7D)
    > + if (!imx6_pcie_supports_suspend(imx6_pcie))
    > return 0;
    >
    > imx6_pcie_assert_core_reset(imx6_pcie);
    > imx6_pcie_init_phy(imx6_pcie);
    > imx6_pcie_deassert_core_reset(imx6_pcie);
    > diff --git a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
    > index 6c1ad160ed87..c1b25f5e386d 100644
    > --- a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
    > +++ b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
    > @@ -438,10 +438,11 @@
    > #define IMX6SX_GPR5_DISP_MUX_DCIC1_LCDIF1 (0x0 << 1)
    > #define IMX6SX_GPR5_DISP_MUX_DCIC1_LVDS (0x1 << 1)
    > #define IMX6SX_GPR5_DISP_MUX_DCIC1_MASK (0x1 << 1)
    >
    > #define IMX6SX_GPR12_PCIE_TEST_POWERDOWN BIT(30)
    > +#define IMX6SX_GPR12_PCIE_PM_TURN_OFF BIT(16)
    > #define IMX6SX_GPR12_PCIE_RX_EQ_MASK (0x7 << 0)
    > #define IMX6SX_GPR12_PCIE_RX_EQ_2 (0x2 << 0)
    >
    > /* For imx6ul iomux gpr register field define */
    > #define IMX6UL_GPR1_ENET1_CLK_DIR (0x1 << 17)
    > --
    > 2.17.1
    >

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