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

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

[Leonard Crestez]

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>
---
 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)
-- 
2.17.1

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

[Leonard Crestez]

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>
---
 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)
-- 
2.17.1

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@nxp.com>

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)
> 

[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@nxp.com>

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)
> 

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

[Philipp Zabel]

Hi Leonard,

On Wed, 2018-10-31 at 11:02 +0000, Leonard Crestez wrote:
> 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@nxp.com>
> 
> 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?

This is a bit out of my wheelhouse, but I'll try my best.

> > ---
> >   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;
> > +	}

I'd use switch(imx6_pcie->variant) for consistency with the other places
where different variants need to be handled separately.

> >   
> >   	/*
> >   	 * 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;
> >   	}

This disables the ref clock. Should this be split into a separate
function imx6_pcie_disable_ref_clk() for symmetry with the already
existing imx6_pcie_enable_ref_clk() ?

That could then also be used to disable pcie_inbound_axi in the error
path of imx6_pcie_deassert_core_reset().

> >   }
> >   
> > +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)
> > 

regards
Philipp

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

[Philipp Zabel]

Hi Leonard,

On Wed, 2018-10-31 at 11:02 +0000, Leonard Crestez wrote:
> 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@nxp.com>
> 
> 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?

This is a bit out of my wheelhouse, but I'll try my best.

> > ---
> >   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;
> > +	}

I'd use switch(imx6_pcie->variant) for consistency with the other places
where different variants need to be handled separately.

> >   
> >   	/*
> >   	 * 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;
> >   	}

This disables the ref clock. Should this be split into a separate
function imx6_pcie_disable_ref_clk() for symmetry with the already
existing imx6_pcie_enable_ref_clk() ?

That could then also be used to disable pcie_inbound_axi in the error
path of imx6_pcie_deassert_core_reset().

> >   }
> >   
> > +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)
> > 

regards
Philipp

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

[Leonard Crestez]

On Thu, 2018-11-01 at 11:02 +0100, Philipp Zabel wrote:
> Hi Leonard,
> 
> On Wed, 2018-10-31 at 11:02 +0000, Leonard Crestez wrote:
> > 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.

> > > +	/*
> > > +	 * 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;
> > > +	}
> 
> I'd use switch(imx6_pcie->variant) for consistency with the other places
> where different variants need to be handled separately.

Yes, this makes sense. But the only thing handle as a variant here
would be 6sx itself, for 7d if (imx6_pcie->turnoff_reset) still makes
sense.

This driver has quite a lot of long functions with switch statements,
maybe some day it should be converted to use a per-soc ops structure?

> > > @@ -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;
> > >   	}
> 
> This disables the ref clock. Should this be split into a separate
> function imx6_pcie_disable_ref_clk() for symmetry with the already
> existing imx6_pcie_enable_ref_clk() ?

Not sure. The symmetry would be limited because enabling requirements
are more stringent than shutdown.

For example the mirror operation on imx7d is done in init_phy instead
of enable_ref_clk. I didn't test but I expect that moving refclk
selection around might violate HW init sequencing requirements so I'd
rather not poke at this.

> That could then also be used to disable pcie_inbound_axi in the error
> path of imx6_pcie_deassert_core_reset().

Not sure, clock disabling on error is also complicated.

In imx6_pcie_deassert_core_reset there is no error path after
enable_ref_clk so there would be nowhere to call disable_ref_clk
outside suspend. In theory imx7d phy pll could fail to lock but we just
print something instead of propagating the error.

If imx6_pcie_establish_link fails clocks could be turned off. It makes
sense to save power if no pcie card is inserted, right? This is what
the imx vendor tree does but my understanding is that this does not
pass compliance testing so I'd rather not upstream this behavior.

See https://source.codeaurora.org/external/imx/linux-imx/tree/drivers/pci/host/pci-imx6.c?h=imx_4.9.88_2.0.0_ga#n1378

Cutting power if the pci slot is empty seems worthwhile but browsing
through other dwc-pci implementations and they don't seem to do this
either.

Instead clocks should stay on if link fails, I guess this is a
requirement for hotplug?

--
Regards,
Leonard

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

[Leonard Crestez]

On Thu, 2018-11-01 at 11:02 +0100, Philipp Zabel wrote:
> Hi Leonard,
> 
> On Wed, 2018-10-31 at 11:02 +0000, Leonard Crestez wrote:
> > 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.

> > > +	/*
> > > +	 * 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;
> > > +	}
> 
> I'd use switch(imx6_pcie->variant) for consistency with the other places
> where different variants need to be handled separately.

Yes, this makes sense. But the only thing handle as a variant here
would be 6sx itself, for 7d if (imx6_pcie->turnoff_reset) still makes
sense.

This driver has quite a lot of long functions with switch statements,
maybe some day it should be converted to use a per-soc ops structure?

> > > @@ -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;
> > >   	}
> 
> This disables the ref clock. Should this be split into a separate
> function imx6_pcie_disable_ref_clk() for symmetry with the already
> existing imx6_pcie_enable_ref_clk() ?

Not sure. The symmetry would be limited because enabling requirements
are more stringent than shutdown.

For example the mirror operation on imx7d is done in init_phy instead
of enable_ref_clk. I didn't test but I expect that moving refclk
selection around might violate HW init sequencing requirements so I'd
rather not poke at this.

> That could then also be used to disable pcie_inbound_axi in the error
> path of imx6_pcie_deassert_core_reset().

Not sure, clock disabling on error is also complicated.

In imx6_pcie_deassert_core_reset there is no error path after
enable_ref_clk so there would be nowhere to call disable_ref_clk
outside suspend. In theory imx7d phy pll could fail to lock but we just
print something instead of propagating the error.

If imx6_pcie_establish_link fails clocks could be turned off. It makes
sense to save power if no pcie card is inserted, right? This is what
the imx vendor tree does but my understanding is that this does not
pass compliance testing so I'd rather not upstream this behavior.

See https://source.codeaurora.org/external/imx/linux-imx/tree/drivers/pci/host/pci-imx6.c?h=imx_4.9.88_2.0.0_ga#n1378

Cutting power if the pci slot is empty seems worthwhile but browsing
through other dwc-pci implementations and they don't seem to do this
either.

Instead clocks should stay on if link fails, I guess this is a
requirement for hotplug?

--
Regards,
Leonard