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Date: Wed, 14 Nov 2018 14:47:37 -0800
From: Andrey Smirnov <andrew.smirnov@...il.com>
To: Leonard Crestez <leonard.crestez@....com>
Cc: Philipp Zabel <p.zabel@...gutronix.de>,
Lucas Stach <l.stach@...gutronix.de>,
Richard Zhu <hongxing.zhu@....com>, lorenzo.pieralisi@....com,
gustavo.pimentel@...opsys.com, Jingoo Han <jingoohan1@...il.com>,
Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
Shawn Guo <shawnguo@...nel.org>,
Fabio Estevam <fabio.estevam@....com>,
Dong Aisheng <aisheng.dong@....com>, linux-imx@....com,
Sascha Hauer <kernel@...gutronix.de>
Subject: Re: [PATCH v2] PCI: imx: Add imx6sx suspend/resume support
On Wed, Nov 7, 2018 at 5:57 AM Leonard Crestez <leonard.crestez@....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@....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@...il.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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