[PATCH v11 resend 0/3] dwc general suspend/resume functionality

[PATCH v11 resend 0/3] dwc general suspend/resume functionality

[Frank Li]

Change log
 - Change from v10 to v11
   Fixed two missed dev_err message change base on Mani's feedback

 - Change from v9 to v10
   min change according to Mani's feedback
   Add Mani's ACK tag

 - Change from v8 to v9
   Reported-by: kernel test robot <lkp@intel.com>
   Closes: https://lore.kernel.org/oe-kbuild-all/202308042251.yGAFqeDw-lkp@intel.com/

 - Change from v7 to v8
   Add new patch to add common PCIE_PME_TO_L2_TIMEOUT_US define.
   timeout value using PCIE_PME_TO_L2_TIMEOUT_US.

 - Chnage from v6 to v7
   Remove local varible struct dw_pcie *pci = pcie->pci
   Change according to Manivannan's feedback
     remove unused lut_off and lut_base
     fixed  100 to 1000(for 1ms)
     using dev_err for timeout
     refine commit message
     fix sleep value 100 (should be 1000 for 1ms).
     use dev_err when timeout

 - Change from v5 to v6
   change to NOIRQ_SYSTEM_SLEEP_PM_OPS to remove #ifdef PM_CONFIG
   refine commit message
   change according to Manivannan's comments.
     remove reduncate step dw_pcie_set_dstate()
     return 0 when .pme_turn_off is zero
     call host_deinit() in suspend
     check .host_deinit and .host_init point before call.

 - Change from v4 to v5
   Closes: https://lore.kernel.org/oe-kbuild-all/202307211904.zExw4Q8H-lkp@intel.com/

 - Change from v3 to v4
   change according to Manivannan's comments.

 - change at v2 to v3
   Basic rewrite whole patch according rob herry suggestion.
   put common function into dwc, so more soc can share the same logic.


Frank Li (2):
  PCI: Add macro PCIE_PME_TO_L2_TIMEOUT_US
  PCI: dwc: Implement general suspend/resume functionality for L2/L3
    transitions

Hou Zhiqiang (1):
  PCI: layerscape: Add power management support for ls1028a

 drivers/pci/controller/dwc/pci-layerscape.c   | 130 ++++++++++++++++--
 .../pci/controller/dwc/pcie-designware-host.c |  76 ++++++++++
 drivers/pci/controller/dwc/pcie-designware.h  |  28 ++++
 drivers/pci/pci.h                             |   6 +
 4 files changed, 231 insertions(+), 9 deletions(-)

-- 
2.34.1

[PATCH v11 1/3] PCI: Add macro PCIE_PME_TO_L2_TIMEOUT_US

[Frank Li]

Introduce the PCIE_PME_TO_L2_TIMEOUT_US macro to facilitate checking the
L2 ready timeout in the PCI subsystem.

Acked-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
 drivers/pci/pci.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index a4c3974340576..da8156663c825 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -13,6 +13,12 @@
 
 #define PCIE_LINK_RETRAIN_TIMEOUT_MS	1000
 
+/*
+ * PCIe r6.0, sec 5.3.3.2.1 <PME Synchronization>
+ * Recommends 1ms to 10ms timeout to check L2 ready.
+ */
+#define PCIE_PME_TO_L2_TIMEOUT_US	10000
+
 extern const unsigned char pcie_link_speed[];
 extern bool pci_early_dump;
 
-- 
2.34.1

[PATCH v11 2/3] PCI: dwc: Implement general suspend/resume functionality for L2/L3 transitions

[Frank Li]

Introduce helper function dw_pcie_get_ltssm() to retrieve SMLH_LTSS_STATE.

Add callback .pme_turn_off and .exit_from_l2 for platform specific PME
handling.

Add common dw_pcie_suspend(resume)_noirq() API to avoid duplicated code
in dwc pci host controller platform driver.

Typical L2 entry workflow/dw_pcie_suspend_noirq()

1. Transmit PME turn off signal to PCI devices and wait for PME_To_Ack.
2. Await link entering L2_IDLE state.

Typical L2 exit workflow/dw_pcie_resume_noirq()

1. Issue exit from L2 command.
2. Reinitialize PCI host.
3. Wait for link to become active.

Acked-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
 .../pci/controller/dwc/pcie-designware-host.c | 76 +++++++++++++++++++
 drivers/pci/controller/dwc/pcie-designware.h  | 29 +++++++
 2 files changed, 105 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 9952057c8819c..cdbff11a7d00e 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -8,6 +8,7 @@
  * Author: Jingoo Han <jg1.han@samsung.com>
  */
 
+#include <linux/iopoll.h>
 #include <linux/irqchip/chained_irq.h>
 #include <linux/irqdomain.h>
 #include <linux/msi.h>
@@ -16,6 +17,7 @@
 #include <linux/pci_regs.h>
 #include <linux/platform_device.h>
 
+#include "../../pci.h"
 #include "pcie-designware.h"
 
 static struct pci_ops dw_pcie_ops;
@@ -807,3 +809,77 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);
+
+int dw_pcie_suspend_noirq(struct dw_pcie *pci)
+{
+	u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+	u32 val;
+	int ret;
+
+	/*
+	 * If L1SS is supported, then do not put the link into L2 as some
+	 * devices such as NVMe expect low resume latency.
+	 */
+	if (dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKCTL) & PCI_EXP_LNKCTL_ASPM_L1)
+		return 0;
+
+	if (dw_pcie_get_ltssm(pci) <= DW_PCIE_LTSSM_DETECT_ACT)
+		return 0;
+
+	if (!pci->pp.ops->pme_turn_off)
+		return 0;
+
+	pci->pp.ops->pme_turn_off(&pci->pp);
+
+	ret = read_poll_timeout(dw_pcie_get_ltssm, val, val == DW_PCIE_LTSSM_L2_IDLE,
+				PCIE_PME_TO_L2_TIMEOUT_US/10,
+				PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
+	if (ret) {
+		dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val);
+		return ret;
+	}
+
+	if (pci->pp.ops->host_deinit)
+		pci->pp.ops->host_deinit(&pci->pp);
+
+	pci->suspended = true;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dw_pcie_suspend_noirq);
+
+int dw_pcie_resume_noirq(struct dw_pcie *pci)
+{
+	int ret;
+
+	if (!pci->suspended)
+		return 0;
+
+	pci->suspended = false;
+
+	if (!pci->pp.ops->exit_from_l2)
+		return 0;
+
+	pci->pp.ops->exit_from_l2(&pci->pp);
+
+	if (pci->pp.ops->host_init) {
+		ret = pci->pp.ops->host_init(&pci->pp);
+		if (ret) {
+			dev_err(pci->dev, "Host init failed: %d\n", ret);
+			return ret;
+		}
+	}
+
+	dw_pcie_setup_rc(&pci->pp);
+
+	ret = dw_pcie_start_link(pci);
+	if (ret)
+		return ret;
+
+	ret = dw_pcie_wait_for_link(pci);
+	if (ret)
+		return ret;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dw_pcie_resume_noirq);
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 79713ce075cc1..629bccfa92ddd 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -288,10 +288,22 @@ enum dw_pcie_core_rst {
 	DW_PCIE_NUM_CORE_RSTS
 };
 
+enum dw_pcie_ltssm {
+	/* Need to align with PCIE_PORT_DEBUG0 bits 0:5 */
+	DW_PCIE_LTSSM_DETECT_QUIET = 0x0,
+	DW_PCIE_LTSSM_DETECT_ACT = 0x1,
+	DW_PCIE_LTSSM_L0 = 0x11,
+	DW_PCIE_LTSSM_L2_IDLE = 0x15,
+
+	DW_PCIE_LTSSM_UNKNOWN = 0xFFFFFFFF,
+};
+
 struct dw_pcie_host_ops {
 	int (*host_init)(struct dw_pcie_rp *pp);
 	void (*host_deinit)(struct dw_pcie_rp *pp);
 	int (*msi_host_init)(struct dw_pcie_rp *pp);
+	void (*pme_turn_off)(struct dw_pcie_rp *pp);
+	void (*exit_from_l2)(struct dw_pcie_rp *pp);
 };
 
 struct dw_pcie_rp {
@@ -364,6 +376,7 @@ struct dw_pcie_ops {
 	void    (*write_dbi2)(struct dw_pcie *pcie, void __iomem *base, u32 reg,
 			      size_t size, u32 val);
 	int	(*link_up)(struct dw_pcie *pcie);
+	enum dw_pcie_ltssm (*get_ltssm)(struct dw_pcie *pcie);
 	int	(*start_link)(struct dw_pcie *pcie);
 	void	(*stop_link)(struct dw_pcie *pcie);
 };
@@ -393,6 +406,7 @@ struct dw_pcie {
 	struct reset_control_bulk_data	app_rsts[DW_PCIE_NUM_APP_RSTS];
 	struct reset_control_bulk_data	core_rsts[DW_PCIE_NUM_CORE_RSTS];
 	struct gpio_desc		*pe_rst;
+	bool			suspended;
 };
 
 #define to_dw_pcie_from_pp(port) container_of((port), struct dw_pcie, pp)
@@ -430,6 +444,9 @@ void dw_pcie_iatu_detect(struct dw_pcie *pci);
 int dw_pcie_edma_detect(struct dw_pcie *pci);
 void dw_pcie_edma_remove(struct dw_pcie *pci);
 
+int dw_pcie_suspend_noirq(struct dw_pcie *pci);
+int dw_pcie_resume_noirq(struct dw_pcie *pci);
+
 static inline void dw_pcie_writel_dbi(struct dw_pcie *pci, u32 reg, u32 val)
 {
 	dw_pcie_write_dbi(pci, reg, 0x4, val);
@@ -501,6 +518,18 @@ static inline void dw_pcie_stop_link(struct dw_pcie *pci)
 		pci->ops->stop_link(pci);
 }
 
+static inline enum dw_pcie_ltssm dw_pcie_get_ltssm(struct dw_pcie *pci)
+{
+	u32 val;
+
+	if (pci->ops && pci->ops->get_ltssm)
+		return pci->ops->get_ltssm(pci);
+
+	val = dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0);
+
+	return (enum dw_pcie_ltssm)FIELD_GET(PORT_LOGIC_LTSSM_STATE_MASK, val);
+}
+
 #ifdef CONFIG_PCIE_DW_HOST
 irqreturn_t dw_handle_msi_irq(struct dw_pcie_rp *pp);
 int dw_pcie_setup_rc(struct dw_pcie_rp *pp);
-- 
2.34.1

[PATCH v11 3/3] PCI: layerscape: Add power management support for ls1028a

[Frank Li]

From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>

Add PME_Turn_off/PME_TO_Ack handshake sequence for ls1028a platform. Call
common dwc dw_pcie_suspend(resume)_noirq() function when system enter/exit
suspend state.

Acked-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
 drivers/pci/controller/dwc/pci-layerscape.c | 130 ++++++++++++++++++--
 1 file changed, 121 insertions(+), 9 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c
index ed5fb492fe084..b49f654335fd7 100644
--- a/drivers/pci/controller/dwc/pci-layerscape.c
+++ b/drivers/pci/controller/dwc/pci-layerscape.c
@@ -8,9 +8,11 @@
  * Author: Minghuan Lian <Minghuan.Lian@freescale.com>
  */
 
+#include <linux/delay.h>
 #include <linux/kernel.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>
+#include <linux/iopoll.h>
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
 #include <linux/of_address.h>
@@ -20,6 +22,7 @@
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
 
+#include "../../pci.h"
 #include "pcie-designware.h"
 
 /* PEX Internal Configuration Registers */
@@ -27,12 +30,26 @@
 #define PCIE_ABSERR		0x8d0 /* Bridge Slave Error Response Register */
 #define PCIE_ABSERR_SETTING	0x9401 /* Forward error of non-posted request */
 
+/* PF Message Command Register */
+#define LS_PCIE_PF_MCR		0x2c
+#define PF_MCR_PTOMR		BIT(0)
+#define PF_MCR_EXL2S		BIT(1)
+
 #define PCIE_IATU_NUM		6
 
+struct ls_pcie_drvdata {
+	const u32 pf_off;
+	bool pm_support;
+};
+
 struct ls_pcie {
 	struct dw_pcie *pci;
+	const struct ls_pcie_drvdata *drvdata;
+	void __iomem *pf_base;
+	bool big_endian;
 };
 
+#define ls_pcie_pf_readl_addr(addr)	ls_pcie_pf_readl(pcie, addr)
 #define to_ls_pcie(x)	dev_get_drvdata((x)->dev)
 
 static bool ls_pcie_is_bridge(struct ls_pcie *pcie)
@@ -73,6 +90,60 @@ static void ls_pcie_fix_error_response(struct ls_pcie *pcie)
 	iowrite32(PCIE_ABSERR_SETTING, pci->dbi_base + PCIE_ABSERR);
 }
 
+static u32 ls_pcie_pf_readl(struct ls_pcie *pcie, u32 off)
+{
+	if (pcie->big_endian)
+		return ioread32be(pcie->pf_base + off);
+
+	return ioread32(pcie->pf_base + off);
+}
+
+static void ls_pcie_pf_writel(struct ls_pcie *pcie, u32 off, u32 val)
+{
+	if (pcie->big_endian)
+		iowrite32be(val, pcie->pf_base + off);
+	else
+		iowrite32(val, pcie->pf_base + off);
+}
+
+static void ls_pcie_send_turnoff_msg(struct dw_pcie_rp *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct ls_pcie *pcie = to_ls_pcie(pci);
+	u32 val;
+	int ret;
+
+	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
+	val |= PF_MCR_PTOMR;
+	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
+
+	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
+				 val, !(val & PF_MCR_PTOMR),
+				 PCIE_PME_TO_L2_TIMEOUT_US/10,
+				 PCIE_PME_TO_L2_TIMEOUT_US);
+	if (ret)
+		dev_err(pcie->pci->dev, "PME_Turn_off timeout\n");
+}
+
+static void ls_pcie_exit_from_l2(struct dw_pcie_rp *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct ls_pcie *pcie = to_ls_pcie(pci);
+	u32 val;
+	int ret;
+
+	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
+	val |= PF_MCR_EXL2S;
+	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
+
+	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
+				 val, !(val & PF_MCR_EXL2S),
+				 PCIE_PME_TO_L2_TIMEOUT_US/10,
+				 PCIE_PME_TO_L2_TIMEOUT_US);
+	if (ret)
+		dev_err(pcie->pci->dev, "L2 exit timeout\n");
+}
+
 static int ls_pcie_host_init(struct dw_pcie_rp *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
@@ -91,18 +162,28 @@ static int ls_pcie_host_init(struct dw_pcie_rp *pp)
 
 static const struct dw_pcie_host_ops ls_pcie_host_ops = {
 	.host_init = ls_pcie_host_init,
+	.pme_turn_off = ls_pcie_send_turnoff_msg,
+	.exit_from_l2 = ls_pcie_exit_from_l2,
+};
+
+static const struct ls_pcie_drvdata ls1021a_drvdata = {
+};
+
+static const struct ls_pcie_drvdata layerscape_drvdata = {
+	.pf_off = 0xc0000,
+	.pm_support = true,
 };
 
 static const struct of_device_id ls_pcie_of_match[] = {
-	{ .compatible = "fsl,ls1012a-pcie", },
-	{ .compatible = "fsl,ls1021a-pcie", },
-	{ .compatible = "fsl,ls1028a-pcie", },
-	{ .compatible = "fsl,ls1043a-pcie", },
-	{ .compatible = "fsl,ls1046a-pcie", },
-	{ .compatible = "fsl,ls2080a-pcie", },
-	{ .compatible = "fsl,ls2085a-pcie", },
-	{ .compatible = "fsl,ls2088a-pcie", },
-	{ .compatible = "fsl,ls1088a-pcie", },
+	{ .compatible = "fsl,ls1012a-pcie", .data = &layerscape_drvdata },
+	{ .compatible = "fsl,ls1021a-pcie", .data = &ls1021a_drvdata },
+	{ .compatible = "fsl,ls1028a-pcie", .data = &layerscape_drvdata },
+	{ .compatible = "fsl,ls1043a-pcie", .data = &ls1021a_drvdata },
+	{ .compatible = "fsl,ls1046a-pcie", .data = &layerscape_drvdata },
+	{ .compatible = "fsl,ls2080a-pcie", .data = &layerscape_drvdata },
+	{ .compatible = "fsl,ls2085a-pcie", .data = &layerscape_drvdata },
+	{ .compatible = "fsl,ls2088a-pcie", .data = &layerscape_drvdata },
+	{ .compatible = "fsl,ls1088a-pcie", .data = &layerscape_drvdata },
 	{ },
 };
 
@@ -121,6 +202,8 @@ static int ls_pcie_probe(struct platform_device *pdev)
 	if (!pci)
 		return -ENOMEM;
 
+	pcie->drvdata = of_device_get_match_data(dev);
+
 	pci->dev = dev;
 	pci->pp.ops = &ls_pcie_host_ops;
 
@@ -131,6 +214,10 @@ static int ls_pcie_probe(struct platform_device *pdev)
 	if (IS_ERR(pci->dbi_base))
 		return PTR_ERR(pci->dbi_base);
 
+	pcie->big_endian = of_property_read_bool(dev->of_node, "big-endian");
+
+	pcie->pf_base = pci->dbi_base + pcie->drvdata->pf_off;
+
 	if (!ls_pcie_is_bridge(pcie))
 		return -ENODEV;
 
@@ -139,12 +226,37 @@ static int ls_pcie_probe(struct platform_device *pdev)
 	return dw_pcie_host_init(&pci->pp);
 }
 
+static int ls_pcie_suspend_noirq(struct device *dev)
+{
+	struct ls_pcie *pcie = dev_get_drvdata(dev);
+
+	if (!pcie->drvdata->pm_support)
+		return 0;
+
+	return dw_pcie_suspend_noirq(pcie->pci);
+}
+
+static int ls_pcie_resume_noirq(struct device *dev)
+{
+	struct ls_pcie *pcie = dev_get_drvdata(dev);
+
+	if (!pcie->drvdata->pm_support)
+		return 0;
+
+	return dw_pcie_resume_noirq(pcie->pci);
+}
+
+static const struct dev_pm_ops ls_pcie_pm_ops = {
+	NOIRQ_SYSTEM_SLEEP_PM_OPS(ls_pcie_suspend_noirq, ls_pcie_resume_noirq)
+};
+
 static struct platform_driver ls_pcie_driver = {
 	.probe = ls_pcie_probe,
 	.driver = {
 		.name = "layerscape-pcie",
 		.of_match_table = ls_pcie_of_match,
 		.suppress_bind_attrs = true,
+		.pm = &ls_pcie_pm_ops,
 	},
 };
 builtin_platform_driver(ls_pcie_driver);
-- 
2.34.1

Re: [PATCH v11 1/3] PCI: Add macro PCIE_PME_TO_L2_TIMEOUT_US

[Lorenzo Pieralisi]

On Wed, Aug 09, 2023 at 11:35:38AM -0400, Frank Li wrote:
> Introduce the PCIE_PME_TO_L2_TIMEOUT_US macro to facilitate checking the
> L2 ready timeout in the PCI subsystem.
> 
> Acked-by: Manivannan Sadhasivam <mani@kernel.org>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
>  drivers/pci/pci.h | 6 ++++++
>  1 file changed, 6 insertions(+)

This patch requires Bjorn's ACK.

Lorenzo

> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index a4c3974340576..da8156663c825 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -13,6 +13,12 @@
>  
>  #define PCIE_LINK_RETRAIN_TIMEOUT_MS	1000
>  
> +/*
> + * PCIe r6.0, sec 5.3.3.2.1 <PME Synchronization>
> + * Recommends 1ms to 10ms timeout to check L2 ready.
> + */
> +#define PCIE_PME_TO_L2_TIMEOUT_US	10000
> +
>  extern const unsigned char pcie_link_speed[];
>  extern bool pci_early_dump;
>  
> -- 
> 2.34.1
> 

Re: [PATCH v11 1/3] PCI: Add macro PCIE_PME_TO_L2_TIMEOUT_US

[Bjorn Helgaas]

On Wed, Aug 09, 2023 at 11:35:38AM -0400, Frank Li wrote:
> Introduce the PCIE_PME_TO_L2_TIMEOUT_US macro to facilitate checking the
> L2 ready timeout in the PCI subsystem.
> 
> Acked-by: Manivannan Sadhasivam <mani@kernel.org>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>

Looks good, thanks!

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  drivers/pci/pci.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index a4c3974340576..da8156663c825 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -13,6 +13,12 @@
>  
>  #define PCIE_LINK_RETRAIN_TIMEOUT_MS	1000
>  
> +/*
> + * PCIe r6.0, sec 5.3.3.2.1 <PME Synchronization>
> + * Recommends 1ms to 10ms timeout to check L2 ready.
> + */
> +#define PCIE_PME_TO_L2_TIMEOUT_US	10000
> +
>  extern const unsigned char pcie_link_speed[];
>  extern bool pci_early_dump;
>  
> -- 
> 2.34.1
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v11 3/3] PCI: layerscape: Add power management support for ls1028a

[Lorenzo Pieralisi]

On Wed, Aug 09, 2023 at 11:35:40AM -0400, Frank Li wrote:
> From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> 
> Add PME_Turn_off/PME_TO_Ack handshake sequence for ls1028a platform. Call
> common dwc dw_pcie_suspend(resume)_noirq() function when system enter/exit
> suspend state.
> 
> Acked-by: Manivannan Sadhasivam <mani@kernel.org>
> Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
>  drivers/pci/controller/dwc/pci-layerscape.c | 130 ++++++++++++++++++--
>  1 file changed, 121 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c
> index ed5fb492fe084..b49f654335fd7 100644
> --- a/drivers/pci/controller/dwc/pci-layerscape.c
> +++ b/drivers/pci/controller/dwc/pci-layerscape.c
> @@ -8,9 +8,11 @@
>   * Author: Minghuan Lian <Minghuan.Lian@freescale.com>
>   */
>  
> +#include <linux/delay.h>
>  #include <linux/kernel.h>
>  #include <linux/interrupt.h>
>  #include <linux/init.h>
> +#include <linux/iopoll.h>
>  #include <linux/of_pci.h>
>  #include <linux/of_platform.h>
>  #include <linux/of_address.h>
> @@ -20,6 +22,7 @@
>  #include <linux/mfd/syscon.h>
>  #include <linux/regmap.h>
>  
> +#include "../../pci.h"
>  #include "pcie-designware.h"
>  
>  /* PEX Internal Configuration Registers */
> @@ -27,12 +30,26 @@
>  #define PCIE_ABSERR		0x8d0 /* Bridge Slave Error Response Register */
>  #define PCIE_ABSERR_SETTING	0x9401 /* Forward error of non-posted request */
>  
> +/* PF Message Command Register */
> +#define LS_PCIE_PF_MCR		0x2c
> +#define PF_MCR_PTOMR		BIT(0)
> +#define PF_MCR_EXL2S		BIT(1)
> +
>  #define PCIE_IATU_NUM		6
>  
> +struct ls_pcie_drvdata {
> +	const u32 pf_off;
> +	bool pm_support;
> +};
> +
>  struct ls_pcie {
>  	struct dw_pcie *pci;
> +	const struct ls_pcie_drvdata *drvdata;
> +	void __iomem *pf_base;
> +	bool big_endian;
>  };
>  
> +#define ls_pcie_pf_readl_addr(addr)	ls_pcie_pf_readl(pcie, addr)
>  #define to_ls_pcie(x)	dev_get_drvdata((x)->dev)
>  
>  static bool ls_pcie_is_bridge(struct ls_pcie *pcie)
> @@ -73,6 +90,60 @@ static void ls_pcie_fix_error_response(struct ls_pcie *pcie)
>  	iowrite32(PCIE_ABSERR_SETTING, pci->dbi_base + PCIE_ABSERR);
>  }
>  
> +static u32 ls_pcie_pf_readl(struct ls_pcie *pcie, u32 off)
> +{
> +	if (pcie->big_endian)
> +		return ioread32be(pcie->pf_base + off);
> +
> +	return ioread32(pcie->pf_base + off);
> +}
> +
> +static void ls_pcie_pf_writel(struct ls_pcie *pcie, u32 off, u32 val)
> +{
> +	if (pcie->big_endian)
> +		iowrite32be(val, pcie->pf_base + off);
> +	else
> +		iowrite32(val, pcie->pf_base + off);
> +}
> +
> +static void ls_pcie_send_turnoff_msg(struct dw_pcie_rp *pp)
> +{
> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +	struct ls_pcie *pcie = to_ls_pcie(pci);
> +	u32 val;
> +	int ret;
> +
> +	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> +	val |= PF_MCR_PTOMR;
> +	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> +
> +	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> +				 val, !(val & PF_MCR_PTOMR),
> +				 PCIE_PME_TO_L2_TIMEOUT_US/10,
> +				 PCIE_PME_TO_L2_TIMEOUT_US);
> +	if (ret)
> +		dev_err(pcie->pci->dev, "PME_Turn_off timeout\n");
> +}
> +
> +static void ls_pcie_exit_from_l2(struct dw_pcie_rp *pp)
> +{
> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +	struct ls_pcie *pcie = to_ls_pcie(pci);
> +	u32 val;
> +	int ret;
> +
> +	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> +	val |= PF_MCR_EXL2S;
> +	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);

What is this write transaction generating in HW ?

Why is it needed ? Shouldn't L2 exit happen automatically
in HW ?

> +
> +	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> +				 val, !(val & PF_MCR_EXL2S),
> +				 PCIE_PME_TO_L2_TIMEOUT_US/10,
> +			PCIE_PME_TO_L2_TIMEOUT_US);

And why is the timeout value the same used for the PME_turn_off message ?

Thanks,
Lorenzo

> +	if (ret)
> +		dev_err(pcie->pci->dev, "L2 exit timeout\n");
> +}
> +
>  static int ls_pcie_host_init(struct dw_pcie_rp *pp)
>  {
>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> @@ -91,18 +162,28 @@ static int ls_pcie_host_init(struct dw_pcie_rp *pp)
>  
>  static const struct dw_pcie_host_ops ls_pcie_host_ops = {
>  	.host_init = ls_pcie_host_init,
> +	.pme_turn_off = ls_pcie_send_turnoff_msg,
> +	.exit_from_l2 = ls_pcie_exit_from_l2,
> +};
> +
> +static const struct ls_pcie_drvdata ls1021a_drvdata = {
> +};
> +
> +static const struct ls_pcie_drvdata layerscape_drvdata = {
> +	.pf_off = 0xc0000,
> +	.pm_support = true,
>  };
>  
>  static const struct of_device_id ls_pcie_of_match[] = {
> -	{ .compatible = "fsl,ls1012a-pcie", },
> -	{ .compatible = "fsl,ls1021a-pcie", },
> -	{ .compatible = "fsl,ls1028a-pcie", },
> -	{ .compatible = "fsl,ls1043a-pcie", },
> -	{ .compatible = "fsl,ls1046a-pcie", },
> -	{ .compatible = "fsl,ls2080a-pcie", },
> -	{ .compatible = "fsl,ls2085a-pcie", },
> -	{ .compatible = "fsl,ls2088a-pcie", },
> -	{ .compatible = "fsl,ls1088a-pcie", },
> +	{ .compatible = "fsl,ls1012a-pcie", .data = &layerscape_drvdata },
> +	{ .compatible = "fsl,ls1021a-pcie", .data = &ls1021a_drvdata },
> +	{ .compatible = "fsl,ls1028a-pcie", .data = &layerscape_drvdata },
> +	{ .compatible = "fsl,ls1043a-pcie", .data = &ls1021a_drvdata },
> +	{ .compatible = "fsl,ls1046a-pcie", .data = &layerscape_drvdata },
> +	{ .compatible = "fsl,ls2080a-pcie", .data = &layerscape_drvdata },
> +	{ .compatible = "fsl,ls2085a-pcie", .data = &layerscape_drvdata },
> +	{ .compatible = "fsl,ls2088a-pcie", .data = &layerscape_drvdata },
> +	{ .compatible = "fsl,ls1088a-pcie", .data = &layerscape_drvdata },
>  	{ },
>  };
>  
> @@ -121,6 +202,8 @@ static int ls_pcie_probe(struct platform_device *pdev)
>  	if (!pci)
>  		return -ENOMEM;
>  
> +	pcie->drvdata = of_device_get_match_data(dev);
> +
>  	pci->dev = dev;
>  	pci->pp.ops = &ls_pcie_host_ops;
>  
> @@ -131,6 +214,10 @@ static int ls_pcie_probe(struct platform_device *pdev)
>  	if (IS_ERR(pci->dbi_base))
>  		return PTR_ERR(pci->dbi_base);
>  
> +	pcie->big_endian = of_property_read_bool(dev->of_node, "big-endian");
> +
> +	pcie->pf_base = pci->dbi_base + pcie->drvdata->pf_off;
> +
>  	if (!ls_pcie_is_bridge(pcie))
>  		return -ENODEV;
>  
> @@ -139,12 +226,37 @@ static int ls_pcie_probe(struct platform_device *pdev)
>  	return dw_pcie_host_init(&pci->pp);
>  }
>  
> +static int ls_pcie_suspend_noirq(struct device *dev)
> +{
> +	struct ls_pcie *pcie = dev_get_drvdata(dev);
> +
> +	if (!pcie->drvdata->pm_support)
> +		return 0;
> +
> +	return dw_pcie_suspend_noirq(pcie->pci);
> +}
> +
> +static int ls_pcie_resume_noirq(struct device *dev)
> +{
> +	struct ls_pcie *pcie = dev_get_drvdata(dev);
> +
> +	if (!pcie->drvdata->pm_support)
> +		return 0;
> +
> +	return dw_pcie_resume_noirq(pcie->pci);
> +}
> +
> +static const struct dev_pm_ops ls_pcie_pm_ops = {
> +	NOIRQ_SYSTEM_SLEEP_PM_OPS(ls_pcie_suspend_noirq, ls_pcie_resume_noirq)
> +};
> +
>  static struct platform_driver ls_pcie_driver = {
>  	.probe = ls_pcie_probe,
>  	.driver = {
>  		.name = "layerscape-pcie",
>  		.of_match_table = ls_pcie_of_match,
>  		.suppress_bind_attrs = true,
> +		.pm = &ls_pcie_pm_ops,
>  	},
>  };
>  builtin_platform_driver(ls_pcie_driver);
> -- 
> 2.34.1
> 

Re: [PATCH v11 3/3] PCI: layerscape: Add power management support for ls1028a

[Frank Li]

On Wed, Aug 16, 2023 at 05:30:10PM +0200, Lorenzo Pieralisi wrote:
> On Wed, Aug 09, 2023 at 11:35:40AM -0400, Frank Li wrote:
> > From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> > 
> > Add PME_Turn_off/PME_TO_Ack handshake sequence for ls1028a platform. Call
> > common dwc dw_pcie_suspend(resume)_noirq() function when system enter/exit
> > suspend state.
> > 
> > Acked-by: Manivannan Sadhasivam <mani@kernel.org>
> > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > ---
> >  drivers/pci/controller/dwc/pci-layerscape.c | 130 ++++++++++++++++++--
> >  1 file changed, 121 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c
> > index ed5fb492fe084..b49f654335fd7 100644
> > --- a/drivers/pci/controller/dwc/pci-layerscape.c
> > +++ b/drivers/pci/controller/dwc/pci-layerscape.c
> > @@ -8,9 +8,11 @@
> >   * Author: Minghuan Lian <Minghuan.Lian@freescale.com>
> >   */
> >  
> > +#include <linux/delay.h>
> >  #include <linux/kernel.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/init.h>
> > +#include <linux/iopoll.h>
> >  #include <linux/of_pci.h>
> >  #include <linux/of_platform.h>
> >  #include <linux/of_address.h>
> > @@ -20,6 +22,7 @@
> >  #include <linux/mfd/syscon.h>
> >  #include <linux/regmap.h>
> >  
> > +#include "../../pci.h"
> >  #include "pcie-designware.h"
> >  
> >  /* PEX Internal Configuration Registers */
> > @@ -27,12 +30,26 @@
> >  #define PCIE_ABSERR		0x8d0 /* Bridge Slave Error Response Register */
> >  #define PCIE_ABSERR_SETTING	0x9401 /* Forward error of non-posted request */
> >  
> > +/* PF Message Command Register */
> > +#define LS_PCIE_PF_MCR		0x2c
> > +#define PF_MCR_PTOMR		BIT(0)
> > +#define PF_MCR_EXL2S		BIT(1)
> > +
> >  #define PCIE_IATU_NUM		6
> >  
> > +struct ls_pcie_drvdata {
> > +	const u32 pf_off;
> > +	bool pm_support;
> > +};
> > +
> >  struct ls_pcie {
> >  	struct dw_pcie *pci;
> > +	const struct ls_pcie_drvdata *drvdata;
> > +	void __iomem *pf_base;
> > +	bool big_endian;
> >  };
> >  
> > +#define ls_pcie_pf_readl_addr(addr)	ls_pcie_pf_readl(pcie, addr)
> >  #define to_ls_pcie(x)	dev_get_drvdata((x)->dev)
> >  
> >  static bool ls_pcie_is_bridge(struct ls_pcie *pcie)
> > @@ -73,6 +90,60 @@ static void ls_pcie_fix_error_response(struct ls_pcie *pcie)
> >  	iowrite32(PCIE_ABSERR_SETTING, pci->dbi_base + PCIE_ABSERR);
> >  }
> >  
> > +static u32 ls_pcie_pf_readl(struct ls_pcie *pcie, u32 off)
> > +{
> > +	if (pcie->big_endian)
> > +		return ioread32be(pcie->pf_base + off);
> > +
> > +	return ioread32(pcie->pf_base + off);
> > +}
> > +
> > +static void ls_pcie_pf_writel(struct ls_pcie *pcie, u32 off, u32 val)
> > +{
> > +	if (pcie->big_endian)
> > +		iowrite32be(val, pcie->pf_base + off);
> > +	else
> > +		iowrite32(val, pcie->pf_base + off);
> > +}
> > +
> > +static void ls_pcie_send_turnoff_msg(struct dw_pcie_rp *pp)
> > +{
> > +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > +	struct ls_pcie *pcie = to_ls_pcie(pci);
> > +	u32 val;
> > +	int ret;
> > +
> > +	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> > +	val |= PF_MCR_PTOMR;
> > +	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> > +
> > +	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> > +				 val, !(val & PF_MCR_PTOMR),
> > +				 PCIE_PME_TO_L2_TIMEOUT_US/10,
> > +				 PCIE_PME_TO_L2_TIMEOUT_US);
> > +	if (ret)
> > +		dev_err(pcie->pci->dev, "PME_Turn_off timeout\n");
> > +}
> > +
> > +static void ls_pcie_exit_from_l2(struct dw_pcie_rp *pp)
> > +{
> > +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > +	struct ls_pcie *pcie = to_ls_pcie(pci);
> > +	u32 val;
> > +	int ret;
> > +
> > +	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> > +	val |= PF_MCR_EXL2S;
> > +	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> 
> What is this write transaction generating in HW ?

I don't think send anything to to pci bus because it was called before
host init.

The spec of ls1028 is not clear enough.

`EXL2S: exit l2 state command. when set to 1, an L2 exit command is
generated. The bit is self clearing. Once the bit is set. SW needs to wait
for the bit to selfclear before sending a new command'

> 
> Why is it needed ? Shouldn't L2 exit happen automatically
> in HW ?

I tried remove this, PCI can't resume. I think this is specific for ls1028
chip to clear internal logic.

> 
> > +
> > +	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> > +				 val, !(val & PF_MCR_EXL2S),
> > +				 PCIE_PME_TO_L2_TIMEOUT_US/10,
> > +			PCIE_PME_TO_L2_TIMEOUT_US);
> 
> And why is the timeout value the same used for the PME_turn_off message ?

I think No spec define it, just reused it. use PCIE_PME_TO_L2_TIMEOUT_US
may cause confuse. What's do you prefered? Just use number,such as 10ms.

> 
> Thanks,
> Lorenzo
> 
> > +	if (ret)
> > +		dev_err(pcie->pci->dev, "L2 exit timeout\n");
> > +}
> > +
> >  static int ls_pcie_host_init(struct dw_pcie_rp *pp)
> >  {
> >  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > @@ -91,18 +162,28 @@ static int ls_pcie_host_init(struct dw_pcie_rp *pp)
> >  
> >  static const struct dw_pcie_host_ops ls_pcie_host_ops = {
> >  	.host_init = ls_pcie_host_init,
> > +	.pme_turn_off = ls_pcie_send_turnoff_msg,
> > +	.exit_from_l2 = ls_pcie_exit_from_l2,
> > +};
> > +
> > +static const struct ls_pcie_drvdata ls1021a_drvdata = {
> > +};
> > +
> > +static const struct ls_pcie_drvdata layerscape_drvdata = {
> > +	.pf_off = 0xc0000,
> > +	.pm_support = true,
> >  };
> >  
> >  static const struct of_device_id ls_pcie_of_match[] = {
> > -	{ .compatible = "fsl,ls1012a-pcie", },
> > -	{ .compatible = "fsl,ls1021a-pcie", },
> > -	{ .compatible = "fsl,ls1028a-pcie", },
> > -	{ .compatible = "fsl,ls1043a-pcie", },
> > -	{ .compatible = "fsl,ls1046a-pcie", },
> > -	{ .compatible = "fsl,ls2080a-pcie", },
> > -	{ .compatible = "fsl,ls2085a-pcie", },
> > -	{ .compatible = "fsl,ls2088a-pcie", },
> > -	{ .compatible = "fsl,ls1088a-pcie", },
> > +	{ .compatible = "fsl,ls1012a-pcie", .data = &layerscape_drvdata },
> > +	{ .compatible = "fsl,ls1021a-pcie", .data = &ls1021a_drvdata },
> > +	{ .compatible = "fsl,ls1028a-pcie", .data = &layerscape_drvdata },
> > +	{ .compatible = "fsl,ls1043a-pcie", .data = &ls1021a_drvdata },
> > +	{ .compatible = "fsl,ls1046a-pcie", .data = &layerscape_drvdata },
> > +	{ .compatible = "fsl,ls2080a-pcie", .data = &layerscape_drvdata },
> > +	{ .compatible = "fsl,ls2085a-pcie", .data = &layerscape_drvdata },
> > +	{ .compatible = "fsl,ls2088a-pcie", .data = &layerscape_drvdata },
> > +	{ .compatible = "fsl,ls1088a-pcie", .data = &layerscape_drvdata },
> >  	{ },
> >  };
> >  
> > @@ -121,6 +202,8 @@ static int ls_pcie_probe(struct platform_device *pdev)
> >  	if (!pci)
> >  		return -ENOMEM;
> >  
> > +	pcie->drvdata = of_device_get_match_data(dev);
> > +
> >  	pci->dev = dev;
> >  	pci->pp.ops = &ls_pcie_host_ops;
> >  
> > @@ -131,6 +214,10 @@ static int ls_pcie_probe(struct platform_device *pdev)
> >  	if (IS_ERR(pci->dbi_base))
> >  		return PTR_ERR(pci->dbi_base);
> >  
> > +	pcie->big_endian = of_property_read_bool(dev->of_node, "big-endian");
> > +
> > +	pcie->pf_base = pci->dbi_base + pcie->drvdata->pf_off;
> > +
> >  	if (!ls_pcie_is_bridge(pcie))
> >  		return -ENODEV;
> >  
> > @@ -139,12 +226,37 @@ static int ls_pcie_probe(struct platform_device *pdev)
> >  	return dw_pcie_host_init(&pci->pp);
> >  }
> >  
> > +static int ls_pcie_suspend_noirq(struct device *dev)
> > +{
> > +	struct ls_pcie *pcie = dev_get_drvdata(dev);
> > +
> > +	if (!pcie->drvdata->pm_support)
> > +		return 0;
> > +
> > +	return dw_pcie_suspend_noirq(pcie->pci);
> > +}
> > +
> > +static int ls_pcie_resume_noirq(struct device *dev)
> > +{
> > +	struct ls_pcie *pcie = dev_get_drvdata(dev);
> > +
> > +	if (!pcie->drvdata->pm_support)
> > +		return 0;
> > +
> > +	return dw_pcie_resume_noirq(pcie->pci);
> > +}
> > +
> > +static const struct dev_pm_ops ls_pcie_pm_ops = {
> > +	NOIRQ_SYSTEM_SLEEP_PM_OPS(ls_pcie_suspend_noirq, ls_pcie_resume_noirq)
> > +};
> > +
> >  static struct platform_driver ls_pcie_driver = {
> >  	.probe = ls_pcie_probe,
> >  	.driver = {
> >  		.name = "layerscape-pcie",
> >  		.of_match_table = ls_pcie_of_match,
> >  		.suppress_bind_attrs = true,
> > +		.pm = &ls_pcie_pm_ops,
> >  	},
> >  };
> >  builtin_platform_driver(ls_pcie_driver);
> > -- 
> > 2.34.1
> > 

Re: [PATCH v11 3/3] PCI: layerscape: Add power management support for ls1028a

[Lorenzo Pieralisi]

On Thu, Aug 17, 2023 at 06:42:50PM -0400, Frank Li wrote:
> On Wed, Aug 16, 2023 at 05:30:10PM +0200, Lorenzo Pieralisi wrote:
> > On Wed, Aug 09, 2023 at 11:35:40AM -0400, Frank Li wrote:
> > > From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> > > 
> > > Add PME_Turn_off/PME_TO_Ack handshake sequence for ls1028a platform. Call
> > > common dwc dw_pcie_suspend(resume)_noirq() function when system enter/exit
> > > suspend state.
> > > 
> > > Acked-by: Manivannan Sadhasivam <mani@kernel.org>
> > > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> > > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > > ---
> > >  drivers/pci/controller/dwc/pci-layerscape.c | 130 ++++++++++++++++++--
> > >  1 file changed, 121 insertions(+), 9 deletions(-)
> > > 
> > > diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c
> > > index ed5fb492fe084..b49f654335fd7 100644
> > > --- a/drivers/pci/controller/dwc/pci-layerscape.c
> > > +++ b/drivers/pci/controller/dwc/pci-layerscape.c
> > > @@ -8,9 +8,11 @@
> > >   * Author: Minghuan Lian <Minghuan.Lian@freescale.com>
> > >   */
> > >  
> > > +#include <linux/delay.h>
> > >  #include <linux/kernel.h>
> > >  #include <linux/interrupt.h>
> > >  #include <linux/init.h>
> > > +#include <linux/iopoll.h>
> > >  #include <linux/of_pci.h>
> > >  #include <linux/of_platform.h>
> > >  #include <linux/of_address.h>
> > > @@ -20,6 +22,7 @@
> > >  #include <linux/mfd/syscon.h>
> > >  #include <linux/regmap.h>
> > >  
> > > +#include "../../pci.h"
> > >  #include "pcie-designware.h"
> > >  
> > >  /* PEX Internal Configuration Registers */
> > > @@ -27,12 +30,26 @@
> > >  #define PCIE_ABSERR		0x8d0 /* Bridge Slave Error Response Register */
> > >  #define PCIE_ABSERR_SETTING	0x9401 /* Forward error of non-posted request */
> > >  
> > > +/* PF Message Command Register */
> > > +#define LS_PCIE_PF_MCR		0x2c
> > > +#define PF_MCR_PTOMR		BIT(0)
> > > +#define PF_MCR_EXL2S		BIT(1)
> > > +
> > >  #define PCIE_IATU_NUM		6
> > >  
> > > +struct ls_pcie_drvdata {
> > > +	const u32 pf_off;
> > > +	bool pm_support;
> > > +};
> > > +
> > >  struct ls_pcie {
> > >  	struct dw_pcie *pci;
> > > +	const struct ls_pcie_drvdata *drvdata;
> > > +	void __iomem *pf_base;
> > > +	bool big_endian;
> > >  };
> > >  
> > > +#define ls_pcie_pf_readl_addr(addr)	ls_pcie_pf_readl(pcie, addr)
> > >  #define to_ls_pcie(x)	dev_get_drvdata((x)->dev)
> > >  
> > >  static bool ls_pcie_is_bridge(struct ls_pcie *pcie)
> > > @@ -73,6 +90,60 @@ static void ls_pcie_fix_error_response(struct ls_pcie *pcie)
> > >  	iowrite32(PCIE_ABSERR_SETTING, pci->dbi_base + PCIE_ABSERR);
> > >  }
> > >  
> > > +static u32 ls_pcie_pf_readl(struct ls_pcie *pcie, u32 off)
> > > +{
> > > +	if (pcie->big_endian)
> > > +		return ioread32be(pcie->pf_base + off);
> > > +
> > > +	return ioread32(pcie->pf_base + off);
> > > +}
> > > +
> > > +static void ls_pcie_pf_writel(struct ls_pcie *pcie, u32 off, u32 val)
> > > +{
> > > +	if (pcie->big_endian)
> > > +		iowrite32be(val, pcie->pf_base + off);
> > > +	else
> > > +		iowrite32(val, pcie->pf_base + off);
> > > +}
> > > +
> > > +static void ls_pcie_send_turnoff_msg(struct dw_pcie_rp *pp)
> > > +{
> > > +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > +	struct ls_pcie *pcie = to_ls_pcie(pci);
> > > +	u32 val;
> > > +	int ret;
> > > +
> > > +	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> > > +	val |= PF_MCR_PTOMR;
> > > +	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> > > +
> > > +	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> > > +				 val, !(val & PF_MCR_PTOMR),
> > > +				 PCIE_PME_TO_L2_TIMEOUT_US/10,
> > > +				 PCIE_PME_TO_L2_TIMEOUT_US);
> > > +	if (ret)
> > > +		dev_err(pcie->pci->dev, "PME_Turn_off timeout\n");
> > > +}
> > > +
> > > +static void ls_pcie_exit_from_l2(struct dw_pcie_rp *pp)
> > > +{
> > > +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > +	struct ls_pcie *pcie = to_ls_pcie(pci);
> > > +	u32 val;
> > > +	int ret;
> > > +
> > > +	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> > > +	val |= PF_MCR_EXL2S;
> > > +	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> > 
> > What is this write transaction generating in HW ?
> 
> I don't think send anything to to pci bus because it was called before
> host init.
> 
> The spec of ls1028 is not clear enough.
> 
> `EXL2S: exit l2 state command. when set to 1, an L2 exit command is
> generated. The bit is self clearing. Once the bit is set. SW needs to wait
> for the bit to selfclear before sending a new command'
> 
> > 
> > Why is it needed ? Shouldn't L2 exit happen automatically
> > in HW ?
> 
> I tried remove this, PCI can't resume. I think this is specific for ls1028
> chip to clear internal logic.

Well, if you don't even know what this does how can you write a sane
device driver ?

Can you ask designers a more detailed description please ?

> > > +
> > > +	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> > > +				 val, !(val & PF_MCR_EXL2S),
> > > +				 PCIE_PME_TO_L2_TIMEOUT_US/10,
> > > +			PCIE_PME_TO_L2_TIMEOUT_US);
> > 
> > And why is the timeout value the same used for the PME_turn_off message ?
> 
> I think No spec define it, just reused it. use PCIE_PME_TO_L2_TIMEOUT_US
> may cause confuse. What's do you prefered? Just use number,such as 10ms.

This delay value is misleading, it is not good to reuse a value for
a delay that is most certainly controller specific.

From this discussion I would say that having pme_turn_off() and
exit_from_l2() hooks is generalizing something we don't know yet
it is needed for all DWC based controllers.

It is probably worth keeping the layerscape specific changes in
the layerscape driver and from there call the "generic" DWC
suspend/resume functions:

dw_pcie_suspend_noirq()
dw_pcie_resume_noirq()

rather than adding hooks that we barely know what they are needed for.

Mani, what do you think ?

Thanks,
Lorenzo

> 
> > 
> > Thanks,
> > Lorenzo
> > 
> > > +	if (ret)
> > > +		dev_err(pcie->pci->dev, "L2 exit timeout\n");
> > > +}
> > > +
> > >  static int ls_pcie_host_init(struct dw_pcie_rp *pp)
> > >  {
> > >  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > @@ -91,18 +162,28 @@ static int ls_pcie_host_init(struct dw_pcie_rp *pp)
> > >  
> > >  static const struct dw_pcie_host_ops ls_pcie_host_ops = {
> > >  	.host_init = ls_pcie_host_init,
> > > +	.pme_turn_off = ls_pcie_send_turnoff_msg,
> > > +	.exit_from_l2 = ls_pcie_exit_from_l2,
> > > +};
> > > +
> > > +static const struct ls_pcie_drvdata ls1021a_drvdata = {
> > > +};
> > > +
> > > +static const struct ls_pcie_drvdata layerscape_drvdata = {
> > > +	.pf_off = 0xc0000,
> > > +	.pm_support = true,
> > >  };
> > >  
> > >  static const struct of_device_id ls_pcie_of_match[] = {
> > > -	{ .compatible = "fsl,ls1012a-pcie", },
> > > -	{ .compatible = "fsl,ls1021a-pcie", },
> > > -	{ .compatible = "fsl,ls1028a-pcie", },
> > > -	{ .compatible = "fsl,ls1043a-pcie", },
> > > -	{ .compatible = "fsl,ls1046a-pcie", },
> > > -	{ .compatible = "fsl,ls2080a-pcie", },
> > > -	{ .compatible = "fsl,ls2085a-pcie", },
> > > -	{ .compatible = "fsl,ls2088a-pcie", },
> > > -	{ .compatible = "fsl,ls1088a-pcie", },
> > > +	{ .compatible = "fsl,ls1012a-pcie", .data = &layerscape_drvdata },
> > > +	{ .compatible = "fsl,ls1021a-pcie", .data = &ls1021a_drvdata },
> > > +	{ .compatible = "fsl,ls1028a-pcie", .data = &layerscape_drvdata },
> > > +	{ .compatible = "fsl,ls1043a-pcie", .data = &ls1021a_drvdata },
> > > +	{ .compatible = "fsl,ls1046a-pcie", .data = &layerscape_drvdata },
> > > +	{ .compatible = "fsl,ls2080a-pcie", .data = &layerscape_drvdata },
> > > +	{ .compatible = "fsl,ls2085a-pcie", .data = &layerscape_drvdata },
> > > +	{ .compatible = "fsl,ls2088a-pcie", .data = &layerscape_drvdata },
> > > +	{ .compatible = "fsl,ls1088a-pcie", .data = &layerscape_drvdata },
> > >  	{ },
> > >  };
> > >  
> > > @@ -121,6 +202,8 @@ static int ls_pcie_probe(struct platform_device *pdev)
> > >  	if (!pci)
> > >  		return -ENOMEM;
> > >  
> > > +	pcie->drvdata = of_device_get_match_data(dev);
> > > +
> > >  	pci->dev = dev;
> > >  	pci->pp.ops = &ls_pcie_host_ops;
> > >  
> > > @@ -131,6 +214,10 @@ static int ls_pcie_probe(struct platform_device *pdev)
> > >  	if (IS_ERR(pci->dbi_base))
> > >  		return PTR_ERR(pci->dbi_base);
> > >  
> > > +	pcie->big_endian = of_property_read_bool(dev->of_node, "big-endian");
> > > +
> > > +	pcie->pf_base = pci->dbi_base + pcie->drvdata->pf_off;
> > > +
> > >  	if (!ls_pcie_is_bridge(pcie))
> > >  		return -ENODEV;
> > >  
> > > @@ -139,12 +226,37 @@ static int ls_pcie_probe(struct platform_device *pdev)
> > >  	return dw_pcie_host_init(&pci->pp);
> > >  }
> > >  
> > > +static int ls_pcie_suspend_noirq(struct device *dev)
> > > +{
> > > +	struct ls_pcie *pcie = dev_get_drvdata(dev);
> > > +
> > > +	if (!pcie->drvdata->pm_support)
> > > +		return 0;
> > > +
> > > +	return dw_pcie_suspend_noirq(pcie->pci);
> > > +}
> > > +
> > > +static int ls_pcie_resume_noirq(struct device *dev)
> > > +{
> > > +	struct ls_pcie *pcie = dev_get_drvdata(dev);
> > > +
> > > +	if (!pcie->drvdata->pm_support)
> > > +		return 0;
> > > +
> > > +	return dw_pcie_resume_noirq(pcie->pci);
> > > +}
> > > +
> > > +static const struct dev_pm_ops ls_pcie_pm_ops = {
> > > +	NOIRQ_SYSTEM_SLEEP_PM_OPS(ls_pcie_suspend_noirq, ls_pcie_resume_noirq)
> > > +};
> > > +
> > >  static struct platform_driver ls_pcie_driver = {
> > >  	.probe = ls_pcie_probe,
> > >  	.driver = {
> > >  		.name = "layerscape-pcie",
> > >  		.of_match_table = ls_pcie_of_match,
> > >  		.suppress_bind_attrs = true,
> > > +		.pm = &ls_pcie_pm_ops,
> > >  	},
> > >  };
> > >  builtin_platform_driver(ls_pcie_driver);
> > > -- 
> > > 2.34.1
> > > 

Re: [PATCH v11 3/3] PCI: layerscape: Add power management support for ls1028a

[Manivannan Sadhasivam]

On Mon, Aug 21, 2023 at 10:21:05AM +0200, Lorenzo Pieralisi wrote:
> On Thu, Aug 17, 2023 at 06:42:50PM -0400, Frank Li wrote:
> > On Wed, Aug 16, 2023 at 05:30:10PM +0200, Lorenzo Pieralisi wrote:
> > > On Wed, Aug 09, 2023 at 11:35:40AM -0400, Frank Li wrote:
> > > > From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> > > > 
> > > > Add PME_Turn_off/PME_TO_Ack handshake sequence for ls1028a platform. Call
> > > > common dwc dw_pcie_suspend(resume)_noirq() function when system enter/exit
> > > > suspend state.
> > > > 
> > > > Acked-by: Manivannan Sadhasivam <mani@kernel.org>
> > > > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> > > > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > > > ---
> > > >  drivers/pci/controller/dwc/pci-layerscape.c | 130 ++++++++++++++++++--
> > > >  1 file changed, 121 insertions(+), 9 deletions(-)
> > > > 
> > > > diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c
> > > > index ed5fb492fe084..b49f654335fd7 100644
> > > > --- a/drivers/pci/controller/dwc/pci-layerscape.c
> > > > +++ b/drivers/pci/controller/dwc/pci-layerscape.c
> > > > @@ -8,9 +8,11 @@
> > > >   * Author: Minghuan Lian <Minghuan.Lian@freescale.com>
> > > >   */
> > > >  
> > > > +#include <linux/delay.h>
> > > >  #include <linux/kernel.h>
> > > >  #include <linux/interrupt.h>
> > > >  #include <linux/init.h>
> > > > +#include <linux/iopoll.h>
> > > >  #include <linux/of_pci.h>
> > > >  #include <linux/of_platform.h>
> > > >  #include <linux/of_address.h>
> > > > @@ -20,6 +22,7 @@
> > > >  #include <linux/mfd/syscon.h>
> > > >  #include <linux/regmap.h>
> > > >  
> > > > +#include "../../pci.h"
> > > >  #include "pcie-designware.h"
> > > >  
> > > >  /* PEX Internal Configuration Registers */
> > > > @@ -27,12 +30,26 @@
> > > >  #define PCIE_ABSERR		0x8d0 /* Bridge Slave Error Response Register */
> > > >  #define PCIE_ABSERR_SETTING	0x9401 /* Forward error of non-posted request */
> > > >  
> > > > +/* PF Message Command Register */
> > > > +#define LS_PCIE_PF_MCR		0x2c
> > > > +#define PF_MCR_PTOMR		BIT(0)
> > > > +#define PF_MCR_EXL2S		BIT(1)
> > > > +
> > > >  #define PCIE_IATU_NUM		6
> > > >  
> > > > +struct ls_pcie_drvdata {
> > > > +	const u32 pf_off;
> > > > +	bool pm_support;
> > > > +};
> > > > +
> > > >  struct ls_pcie {
> > > >  	struct dw_pcie *pci;
> > > > +	const struct ls_pcie_drvdata *drvdata;
> > > > +	void __iomem *pf_base;
> > > > +	bool big_endian;
> > > >  };
> > > >  
> > > > +#define ls_pcie_pf_readl_addr(addr)	ls_pcie_pf_readl(pcie, addr)
> > > >  #define to_ls_pcie(x)	dev_get_drvdata((x)->dev)
> > > >  
> > > >  static bool ls_pcie_is_bridge(struct ls_pcie *pcie)
> > > > @@ -73,6 +90,60 @@ static void ls_pcie_fix_error_response(struct ls_pcie *pcie)
> > > >  	iowrite32(PCIE_ABSERR_SETTING, pci->dbi_base + PCIE_ABSERR);
> > > >  }
> > > >  
> > > > +static u32 ls_pcie_pf_readl(struct ls_pcie *pcie, u32 off)
> > > > +{
> > > > +	if (pcie->big_endian)
> > > > +		return ioread32be(pcie->pf_base + off);
> > > > +
> > > > +	return ioread32(pcie->pf_base + off);
> > > > +}
> > > > +
> > > > +static void ls_pcie_pf_writel(struct ls_pcie *pcie, u32 off, u32 val)
> > > > +{
> > > > +	if (pcie->big_endian)
> > > > +		iowrite32be(val, pcie->pf_base + off);
> > > > +	else
> > > > +		iowrite32(val, pcie->pf_base + off);
> > > > +}
> > > > +
> > > > +static void ls_pcie_send_turnoff_msg(struct dw_pcie_rp *pp)
> > > > +{
> > > > +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > > +	struct ls_pcie *pcie = to_ls_pcie(pci);
> > > > +	u32 val;
> > > > +	int ret;
> > > > +
> > > > +	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> > > > +	val |= PF_MCR_PTOMR;
> > > > +	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> > > > +
> > > > +	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> > > > +				 val, !(val & PF_MCR_PTOMR),
> > > > +				 PCIE_PME_TO_L2_TIMEOUT_US/10,
> > > > +				 PCIE_PME_TO_L2_TIMEOUT_US);
> > > > +	if (ret)
> > > > +		dev_err(pcie->pci->dev, "PME_Turn_off timeout\n");
> > > > +}
> > > > +
> > > > +static void ls_pcie_exit_from_l2(struct dw_pcie_rp *pp)
> > > > +{
> > > > +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > > +	struct ls_pcie *pcie = to_ls_pcie(pci);
> > > > +	u32 val;
> > > > +	int ret;
> > > > +
> > > > +	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> > > > +	val |= PF_MCR_EXL2S;
> > > > +	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> > > 
> > > What is this write transaction generating in HW ?
> > 
> > I don't think send anything to to pci bus because it was called before
> > host init.
> > 
> > The spec of ls1028 is not clear enough.
> > 
> > `EXL2S: exit l2 state command. when set to 1, an L2 exit command is
> > generated. The bit is self clearing. Once the bit is set. SW needs to wait
> > for the bit to selfclear before sending a new command'
> > 
> > > 
> > > Why is it needed ? Shouldn't L2 exit happen automatically
> > > in HW ?
> > 
> > I tried remove this, PCI can't resume. I think this is specific for ls1028
> > chip to clear internal logic.
> 
> Well, if you don't even know what this does how can you write a sane
> device driver ?
> 
> Can you ask designers a more detailed description please ?
> 

I often encounter hw quirks like this one and the hw designers will just say
that "set bit X to make Y happpen". IMO a comment saying that the driver need to
set PF_MCR_EXL2S bit in LS_PCIE_PF_MCR register for the link to exit L2 state is
good enough.

> > > > +
> > > > +	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> > > > +				 val, !(val & PF_MCR_EXL2S),
> > > > +				 PCIE_PME_TO_L2_TIMEOUT_US/10,
> > > > +			PCIE_PME_TO_L2_TIMEOUT_US);
> > > 
> > > And why is the timeout value the same used for the PME_turn_off message ?
> > 
> > I think No spec define it, just reused it. use PCIE_PME_TO_L2_TIMEOUT_US
> > may cause confuse. What's do you prefered? Just use number,such as 10ms.
> 
> This delay value is misleading, it is not good to reuse a value for
> a delay that is most certainly controller specific.
> 
> From this discussion I would say that having pme_turn_off() and
> exit_from_l2() hooks is generalizing something we don't know yet
> it is needed for all DWC based controllers.
> 
> It is probably worth keeping the layerscape specific changes in
> the layerscape driver and from there call the "generic" DWC
> suspend/resume functions:
> 
> dw_pcie_suspend_noirq()
> dw_pcie_resume_noirq()
> 
> rather than adding hooks that we barely know what they are needed for.
> 
> Mani, what do you think ?
> 

PME_Turn_off procedure may vary between controllers and is really required
from core DWC perspective. So I'd prefer to keep the pme_turn_off() callback
and leave exit_from_l2() since later seems to be only required for layerscape.

- Mani

-- 
மணிவண்ணன் சதாசிவம்

Re: [PATCH v11 3/3] PCI: layerscape: Add power management support for ls1028a

[Frank Li]

On Mon, Aug 21, 2023 at 04:03:57PM +0530, Manivannan Sadhasivam wrote:
> On Mon, Aug 21, 2023 at 10:21:05AM +0200, Lorenzo Pieralisi wrote:
> > On Thu, Aug 17, 2023 at 06:42:50PM -0400, Frank Li wrote:
> > > On Wed, Aug 16, 2023 at 05:30:10PM +0200, Lorenzo Pieralisi wrote:
> > > > On Wed, Aug 09, 2023 at 11:35:40AM -0400, Frank Li wrote:
> > > > > From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> > > > > 
> > > > > Add PME_Turn_off/PME_TO_Ack handshake sequence for ls1028a platform. Call
> > > > > common dwc dw_pcie_suspend(resume)_noirq() function when system enter/exit
> > > > > suspend state.
> > > > > 
> > > > > Acked-by: Manivannan Sadhasivam <mani@kernel.org>
> > > > > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> > > > > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > > > > ---
> > > > >  drivers/pci/controller/dwc/pci-layerscape.c | 130 ++++++++++++++++++--
> > > > >  1 file changed, 121 insertions(+), 9 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c
> > > > > index ed5fb492fe084..b49f654335fd7 100644
> > > > > --- a/drivers/pci/controller/dwc/pci-layerscape.c
> > > > > +++ b/drivers/pci/controller/dwc/pci-layerscape.c
> > > > > @@ -8,9 +8,11 @@
> > > > >   * Author: Minghuan Lian <Minghuan.Lian@freescale.com>
> > > > >   */
> > > > >  
> > > > > +#include <linux/delay.h>
> > > > >  #include <linux/kernel.h>
> > > > >  #include <linux/interrupt.h>
> > > > >  #include <linux/init.h>
> > > > > +#include <linux/iopoll.h>
> > > > >  #include <linux/of_pci.h>
> > > > >  #include <linux/of_platform.h>
> > > > >  #include <linux/of_address.h>
> > > > > @@ -20,6 +22,7 @@
> > > > >  #include <linux/mfd/syscon.h>
> > > > >  #include <linux/regmap.h>
> > > > >  
> > > > > +#include "../../pci.h"
> > > > >  #include "pcie-designware.h"
> > > > >  
> > > > >  /* PEX Internal Configuration Registers */
> > > > > @@ -27,12 +30,26 @@
> > > > >  #define PCIE_ABSERR		0x8d0 /* Bridge Slave Error Response Register */
> > > > >  #define PCIE_ABSERR_SETTING	0x9401 /* Forward error of non-posted request */
> > > > >  
> > > > > +/* PF Message Command Register */
> > > > > +#define LS_PCIE_PF_MCR		0x2c
> > > > > +#define PF_MCR_PTOMR		BIT(0)
> > > > > +#define PF_MCR_EXL2S		BIT(1)
> > > > > +
> > > > >  #define PCIE_IATU_NUM		6
> > > > >  
> > > > > +struct ls_pcie_drvdata {
> > > > > +	const u32 pf_off;
> > > > > +	bool pm_support;
> > > > > +};
> > > > > +
> > > > >  struct ls_pcie {
> > > > >  	struct dw_pcie *pci;
> > > > > +	const struct ls_pcie_drvdata *drvdata;
> > > > > +	void __iomem *pf_base;
> > > > > +	bool big_endian;
> > > > >  };
> > > > >  
> > > > > +#define ls_pcie_pf_readl_addr(addr)	ls_pcie_pf_readl(pcie, addr)
> > > > >  #define to_ls_pcie(x)	dev_get_drvdata((x)->dev)
> > > > >  
> > > > >  static bool ls_pcie_is_bridge(struct ls_pcie *pcie)
> > > > > @@ -73,6 +90,60 @@ static void ls_pcie_fix_error_response(struct ls_pcie *pcie)
> > > > >  	iowrite32(PCIE_ABSERR_SETTING, pci->dbi_base + PCIE_ABSERR);
> > > > >  }
> > > > >  
> > > > > +static u32 ls_pcie_pf_readl(struct ls_pcie *pcie, u32 off)
> > > > > +{
> > > > > +	if (pcie->big_endian)
> > > > > +		return ioread32be(pcie->pf_base + off);
> > > > > +
> > > > > +	return ioread32(pcie->pf_base + off);
> > > > > +}
> > > > > +
> > > > > +static void ls_pcie_pf_writel(struct ls_pcie *pcie, u32 off, u32 val)
> > > > > +{
> > > > > +	if (pcie->big_endian)
> > > > > +		iowrite32be(val, pcie->pf_base + off);
> > > > > +	else
> > > > > +		iowrite32(val, pcie->pf_base + off);
> > > > > +}
> > > > > +
> > > > > +static void ls_pcie_send_turnoff_msg(struct dw_pcie_rp *pp)
> > > > > +{
> > > > > +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > > > +	struct ls_pcie *pcie = to_ls_pcie(pci);
> > > > > +	u32 val;
> > > > > +	int ret;
> > > > > +
> > > > > +	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> > > > > +	val |= PF_MCR_PTOMR;
> > > > > +	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> > > > > +
> > > > > +	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> > > > > +				 val, !(val & PF_MCR_PTOMR),
> > > > > +				 PCIE_PME_TO_L2_TIMEOUT_US/10,
> > > > > +				 PCIE_PME_TO_L2_TIMEOUT_US);
> > > > > +	if (ret)
> > > > > +		dev_err(pcie->pci->dev, "PME_Turn_off timeout\n");
> > > > > +}
> > > > > +
> > > > > +static void ls_pcie_exit_from_l2(struct dw_pcie_rp *pp)
> > > > > +{
> > > > > +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > > > +	struct ls_pcie *pcie = to_ls_pcie(pci);
> > > > > +	u32 val;
> > > > > +	int ret;
> > > > > +
> > > > > +	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> > > > > +	val |= PF_MCR_EXL2S;
> > > > > +	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> > > > 
> > > > What is this write transaction generating in HW ?
> > > 
> > > I don't think send anything to to pci bus because it was called before
> > > host init.
> > > 
> > > The spec of ls1028 is not clear enough.
> > > 
> > > `EXL2S: exit l2 state command. when set to 1, an L2 exit command is
> > > generated. The bit is self clearing. Once the bit is set. SW needs to wait
> > > for the bit to selfclear before sending a new command'
> > > 
> > > > 
> > > > Why is it needed ? Shouldn't L2 exit happen automatically
> > > > in HW ?
> > > 
> > > I tried remove this, PCI can't resume. I think this is specific for ls1028
> > > chip to clear internal logic.
> > 
> > Well, if you don't even know what this does how can you write a sane
> > device driver ?
> > 
> > Can you ask designers a more detailed description please ?
> > 
> 
> I often encounter hw quirks like this one and the hw designers will just say
> that "set bit X to make Y happpen". IMO a comment saying that the driver need to
> set PF_MCR_EXL2S bit in LS_PCIE_PF_MCR register for the link to exit L2 state is
> good enough.
> 
> > > > > +
> > > > > +	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> > > > > +				 val, !(val & PF_MCR_EXL2S),
> > > > > +				 PCIE_PME_TO_L2_TIMEOUT_US/10,
> > > > > +			PCIE_PME_TO_L2_TIMEOUT_US);
> > > > 
> > > > And why is the timeout value the same used for the PME_turn_off message ?
> > > 
> > > I think No spec define it, just reused it. use PCIE_PME_TO_L2_TIMEOUT_US
> > > may cause confuse. What's do you prefered? Just use number,such as 10ms.
> > 
> > This delay value is misleading, it is not good to reuse a value for
> > a delay that is most certainly controller specific.
> > 
> > From this discussion I would say that having pme_turn_off() and
> > exit_from_l2() hooks is generalizing something we don't know yet
> > it is needed for all DWC based controllers.
> > 
> > It is probably worth keeping the layerscape specific changes in
> > the layerscape driver and from there call the "generic" DWC
> > suspend/resume functions:
> > 
> > dw_pcie_suspend_noirq()
> > dw_pcie_resume_noirq()
> > 
> > rather than adding hooks that we barely know what they are needed for.
> > 
> > Mani, what do you think ?
> > 
> 
> PME_Turn_off procedure may vary between controllers and is really required
> from core DWC perspective. So I'd prefer to keep the pme_turn_off() callback
> and leave exit_from_l2() since later seems to be only required for layerscape.

There are at least two chips that need use exit_from_l2 at layerscape
platform. I think not all dwc platforms implement suspend/resume yet. 
Maybe some platform need it also. Of course I can leave it to layerscape
driver. we can change when new platform really need it.

Frank

> 
> - Mani
> 
> -- 
> மணிவண்ணன் சதாசிவம்