Re: [PATCH] PCI: imx: Add imx6sx suspend/resume support

[Leonard Crestez]

On 10/8/2018 8:38 PM, Leonard Crestez 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@xxxxxxx>

This is a gentle reminder that this patch was posted ~3 weeks ago and 
there is yet no reply. It's a mostly straight-forward extension of imx7d 
pci suspend/resume support to a different SOC.

Lucas/Philipp: can you please take a brief look?

> ---
>   drivers/pci/controller/dwc/pci-imx6.c       | 40 ++++++++++++++++++---
>   include/linux/mfd/syscon/imx6q-iomuxc-gpr.h |  1 +
>   2 files changed, 36 insertions(+), 5 deletions(-)
> 
> Patch is again linux-next, meant to apply here:
>   https://git.kernel.org/pub/scm/linux/kernel/git/lpieralisi/pci.git/log/?h=pci/dwc
> 
> This is quite an old patch, mostly did it to prove that imx7d suspend
> support is indeed generic.
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 2cbef2d7c207..6171171db1fc 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -771,12 +771,29 @@ 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 while
> +	 * others poke at iomuxc registers.
> +	 */
> +	if (imx6_pcie->turnoff_reset) {
> +		reset_control_assert(imx6_pcie->turnoff_reset);
> +		reset_control_deassert(imx6_pcie->turnoff_reset);
> +	} else if (imx6_pcie->variant == 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);
> +	} else {
> +		dev_err(dev, "PME_Turn_Off not implemented\n");
> +		return;
> +	}
>   
>   	/*
>   	 * Components with an upstream port must respond to
>   	 * PME_Turn_Off with PME_TO_Ack but we can't check.
>   	 *
> @@ -790,22 +807,35 @@ 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 +847,11 @@ 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)
>