diff mbox series

[v4,4/9] PCI/PTM: Add pci_suspend_ptm() and pci_resume_ptm()

Message ID 20220909202505.314195-5-helgaas@kernel.org
State New
Headers show
Series PCI/PM: Always disable PTM for all devices during suspend | expand

Commit Message

Bjorn Helgaas Sept. 9, 2022, 8:25 p.m. UTC 
From: Bjorn Helgaas <bhelgaas@google.com>

We disable PTM during suspend because that allows some Root Ports to enter
lower-power PM states, which means we also need to disable PTM for all
downstream devices.  Add pci_suspend_ptm() and pci_resume_ptm() for this
purpose.

pci_enable_ptm() and pci_disable_ptm() are for drivers to use to enable or
disable PTM.  They use dev->ptm_enabled to keep track of whether PTM should
be enabled.

pci_suspend_ptm() and pci_resume_ptm() are PCI core-internal functions to
temporarily disable PTM during suspend and (depending on dev->ptm_enabled)
re-enable PTM during resume.

Enable/disable/suspend/resume all use internal __pci_enable_ptm() and
__pci_disable_ptm() functions that only update the PTM Control register.
Outline:

  pci_enable_ptm(struct pci_dev *dev)
  {
     __pci_enable_ptm(dev);
     dev->ptm_enabled = 1;
     pci_ptm_info(dev);
  }

  pci_disable_ptm(struct pci_dev *dev)
  {
     if (dev->ptm_enabled) {
       __pci_disable_ptm(dev);
       dev->ptm_enabled = 0;
     }
  }

  pci_suspend_ptm(struct pci_dev *dev)
  {
     if (dev->ptm_enabled)
       __pci_disable_ptm(dev);
  }

  pci_resume_ptm(struct pci_dev *dev)
  {
     if (dev->ptm_enabled)
       __pci_enable_ptm(dev);
  }

Nothing currently calls pci_resume_ptm(); the suspend path saves the PTM
state before disabling PTM, so the PTM state restore in the resume path
implicitly re-enables it.  A future change will use pci_resume_ptm() to fix
some problems with this approach.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/pci.c      |  4 +--
 drivers/pci/pci.h      |  6 ++--
 drivers/pci/pcie/ptm.c | 71 +++++++++++++++++++++++++++++++++---------
 include/linux/pci.h    |  2 ++
 4 files changed, 65 insertions(+), 18 deletions(-)

Comments

Kuppuswamy Sathyanarayanan Sept. 9, 2022, 11:44 p.m. UTC | #1 
On 9/9/22 1:25 PM, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@google.com>
> 
> We disable PTM during suspend because that allows some Root Ports to enter
> lower-power PM states, which means we also need to disable PTM for all
> downstream devices.  Add pci_suspend_ptm() and pci_resume_ptm() for this
> purpose.
> 
> pci_enable_ptm() and pci_disable_ptm() are for drivers to use to enable or
> disable PTM.  They use dev->ptm_enabled to keep track of whether PTM should
> be enabled.
> 
> pci_suspend_ptm() and pci_resume_ptm() are PCI core-internal functions to
> temporarily disable PTM during suspend and (depending on dev->ptm_enabled)
> re-enable PTM during resume.
> 
> Enable/disable/suspend/resume all use internal __pci_enable_ptm() and
> __pci_disable_ptm() functions that only update the PTM Control register.
> Outline:
> 
>   pci_enable_ptm(struct pci_dev *dev)
>   {
>      __pci_enable_ptm(dev);
>      dev->ptm_enabled = 1;
>      pci_ptm_info(dev);
>   }
> 
>   pci_disable_ptm(struct pci_dev *dev)
>   {
>      if (dev->ptm_enabled) {
>        __pci_disable_ptm(dev);
>        dev->ptm_enabled = 0;
>      }
>   }
> 
>   pci_suspend_ptm(struct pci_dev *dev)
>   {
>      if (dev->ptm_enabled)
>        __pci_disable_ptm(dev);
>   }
> 
>   pci_resume_ptm(struct pci_dev *dev)
>   {
>      if (dev->ptm_enabled)
>        __pci_enable_ptm(dev);
>   }
> 
> Nothing currently calls pci_resume_ptm(); the suspend path saves the PTM

Is semicolon intentional ?

> state before disabling PTM, so the PTM state restore in the resume path
> implicitly re-enables it.  A future change will use pci_resume_ptm() to fix
> some problems with this approach.
> 
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
>  drivers/pci/pci.c      |  4 +--
>  drivers/pci/pci.h      |  6 ++--
>  drivers/pci/pcie/ptm.c | 71 +++++++++++++++++++++++++++++++++---------
>  include/linux/pci.h    |  2 ++
>  4 files changed, 65 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 95bc329e74c0..83818f81577d 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2714,7 +2714,7 @@ int pci_prepare_to_sleep(struct pci_dev *dev)
>  	 * lower-power idle state as a whole.
>  	 */
>  	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
> -		pci_disable_ptm(dev);
> +		pci_suspend_ptm(dev);
>  
>  	pci_enable_wake(dev, target_state, wakeup);
>  
> @@ -2772,7 +2772,7 @@ int pci_finish_runtime_suspend(struct pci_dev *dev)
>  	 * lower-power idle state as a whole.
>  	 */
>  	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
> -		pci_disable_ptm(dev);
> +		pci_suspend_ptm(dev);
>  
>  	__pci_enable_wake(dev, target_state, pci_dev_run_wake(dev));
>  
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 785f31086313..ce4a277e3f41 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -507,11 +507,13 @@ static inline int pci_iov_bus_range(struct pci_bus *bus)
>  #ifdef CONFIG_PCIE_PTM
>  void pci_save_ptm_state(struct pci_dev *dev);
>  void pci_restore_ptm_state(struct pci_dev *dev);
> -void pci_disable_ptm(struct pci_dev *dev);
> +void pci_suspend_ptm(struct pci_dev *dev);
> +void pci_resume_ptm(struct pci_dev *dev);
>  #else
>  static inline void pci_save_ptm_state(struct pci_dev *dev) { }
>  static inline void pci_restore_ptm_state(struct pci_dev *dev) { }
> -static inline void pci_disable_ptm(struct pci_dev *dev) { }
> +static inline void pci_suspend_ptm(struct pci_dev *dev) { }
> +static inline void pci_resume_ptm(struct pci_dev *dev) { }
>  #endif
>  
>  unsigned long pci_cardbus_resource_alignment(struct resource *);
> diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
> index ba1d50c965fa..70a28b74e721 100644
> --- a/drivers/pci/pcie/ptm.c
> +++ b/drivers/pci/pcie/ptm.c
> @@ -29,7 +29,7 @@ static void pci_ptm_info(struct pci_dev *dev)
>  		 dev->ptm_root ? " (root)" : "", clock_desc);
>  }
>  
> -void pci_disable_ptm(struct pci_dev *dev)
> +static void __pci_disable_ptm(struct pci_dev *dev)
>  {
>  	u16 ptm = dev->ptm_cap;
>  	u16 ctrl;
> @@ -42,6 +42,21 @@ void pci_disable_ptm(struct pci_dev *dev)
>  	pci_write_config_word(dev, ptm + PCI_PTM_CTRL, ctrl);
>  }
>  
> +/**
> + * pci_disable_ptm() - Disable Precision Time Measurement
> + * @dev: PCI device
> + *
> + * Disable Precision Time Measurement for @dev.
> + */
> +void pci_disable_ptm(struct pci_dev *dev)
> +{
> +	if (dev->ptm_enabled) {
> +		__pci_disable_ptm(dev);
> +		dev->ptm_enabled = 0;
> +	}
> +}
> +EXPORT_SYMBOL(pci_disable_ptm);
> +
>  void pci_save_ptm_state(struct pci_dev *dev)
>  {
>  	u16 ptm = dev->ptm_cap;
> @@ -151,18 +166,8 @@ void pci_ptm_init(struct pci_dev *dev)
>  		pci_enable_ptm(dev, NULL);
>  }
>  
> -/**
> - * pci_enable_ptm() - Enable Precision Time Measurement
> - * @dev: PCI device
> - * @granularity: pointer to return granularity
> - *
> - * Enable Precision Time Measurement for @dev.  If successful and
> - * @granularity is non-NULL, return the Effective Granularity.
> - *
> - * Return: zero if successful, or -EINVAL if @dev lacks a PTM Capability or
> - * is not a PTM Root and lacks an upstream path of PTM-enabled devices.
> - */
> -int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
> +/* Enable PTM in the Control register if possible */
> +static int __pci_enable_ptm(struct pci_dev *dev)
>  {
>  	u16 ptm = dev->ptm_cap;
>  	struct pci_dev *ups;
> @@ -191,8 +196,29 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
>  		ctrl |= PCI_PTM_CTRL_ROOT;
>  
>  	pci_write_config_dword(dev, ptm + PCI_PTM_CTRL, ctrl);
> +	return 0;
> +}
> +
> +/**
> + * pci_enable_ptm() - Enable Precision Time Measurement
> + * @dev: PCI device
> + * @granularity: pointer to return granularity
> + *
> + * Enable Precision Time Measurement for @dev.  If successful and
> + * @granularity is non-NULL, return the Effective Granularity.
> + *
> + * Return: zero if successful, or -EINVAL if @dev lacks a PTM Capability or
> + * is not a PTM Root and lacks an upstream path of PTM-enabled devices.
> + */
> +int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
> +{
> +	int rc;
> +
> +	rc = __pci_enable_ptm(dev);
> +	if (rc)
> +		return rc;
> +
>  	dev->ptm_enabled = 1;
> -
>  	pci_ptm_info(dev);
>  
>  	if (granularity)
> @@ -201,6 +227,23 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
>  }
>  EXPORT_SYMBOL(pci_enable_ptm);
>  
> +/*
> + * Disable PTM, but preserve dev->ptm_enabled so we silently re-enable it on
> + * resume if necessary.
> + */
> +void pci_suspend_ptm(struct pci_dev *dev)
> +{
> +	if (dev->ptm_enabled)
> +		__pci_disable_ptm(dev);
> +}
> +
> +/* If PTM was enabled before suspend, re-enable it when resuming */
> +void pci_resume_ptm(struct pci_dev *dev)
> +{
> +	if (dev->ptm_enabled)
> +		__pci_enable_ptm(dev);
> +}
> +
>  bool pcie_ptm_enabled(struct pci_dev *dev)
>  {
>  	if (!dev)
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 54be939023a3..cb5f796e3319 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1678,10 +1678,12 @@ bool pci_ats_disabled(void);
>  
>  #ifdef CONFIG_PCIE_PTM
>  int pci_enable_ptm(struct pci_dev *dev, u8 *granularity);
> +void pci_disable_ptm(struct pci_dev *dev);
>  bool pcie_ptm_enabled(struct pci_dev *dev);
>  #else
>  static inline int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
>  { return -EINVAL; }
> +static inline void pci_disable_ptm(struct pci_dev *dev) { }
>  static inline bool pcie_ptm_enabled(struct pci_dev *dev)
>  { return false; }
>  #endif
diff mbox series

Patch

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 95bc329e74c0..83818f81577d 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2714,7 +2714,7 @@  int pci_prepare_to_sleep(struct pci_dev *dev)
 	 * lower-power idle state as a whole.
 	 */
 	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
-		pci_disable_ptm(dev);
+		pci_suspend_ptm(dev);
 
 	pci_enable_wake(dev, target_state, wakeup);
 
@@ -2772,7 +2772,7 @@  int pci_finish_runtime_suspend(struct pci_dev *dev)
 	 * lower-power idle state as a whole.
 	 */
 	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
-		pci_disable_ptm(dev);
+		pci_suspend_ptm(dev);
 
 	__pci_enable_wake(dev, target_state, pci_dev_run_wake(dev));
 
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 785f31086313..ce4a277e3f41 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -507,11 +507,13 @@  static inline int pci_iov_bus_range(struct pci_bus *bus)
 #ifdef CONFIG_PCIE_PTM
 void pci_save_ptm_state(struct pci_dev *dev);
 void pci_restore_ptm_state(struct pci_dev *dev);
-void pci_disable_ptm(struct pci_dev *dev);
+void pci_suspend_ptm(struct pci_dev *dev);
+void pci_resume_ptm(struct pci_dev *dev);
 #else
 static inline void pci_save_ptm_state(struct pci_dev *dev) { }
 static inline void pci_restore_ptm_state(struct pci_dev *dev) { }
-static inline void pci_disable_ptm(struct pci_dev *dev) { }
+static inline void pci_suspend_ptm(struct pci_dev *dev) { }
+static inline void pci_resume_ptm(struct pci_dev *dev) { }
 #endif
 
 unsigned long pci_cardbus_resource_alignment(struct resource *);
diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
index ba1d50c965fa..70a28b74e721 100644
--- a/drivers/pci/pcie/ptm.c
+++ b/drivers/pci/pcie/ptm.c
@@ -29,7 +29,7 @@  static void pci_ptm_info(struct pci_dev *dev)
 		 dev->ptm_root ? " (root)" : "", clock_desc);
 }
 
-void pci_disable_ptm(struct pci_dev *dev)
+static void __pci_disable_ptm(struct pci_dev *dev)
 {
 	u16 ptm = dev->ptm_cap;
 	u16 ctrl;
@@ -42,6 +42,21 @@  void pci_disable_ptm(struct pci_dev *dev)
 	pci_write_config_word(dev, ptm + PCI_PTM_CTRL, ctrl);
 }
 
+/**
+ * pci_disable_ptm() - Disable Precision Time Measurement
+ * @dev: PCI device
+ *
+ * Disable Precision Time Measurement for @dev.
+ */
+void pci_disable_ptm(struct pci_dev *dev)
+{
+	if (dev->ptm_enabled) {
+		__pci_disable_ptm(dev);
+		dev->ptm_enabled = 0;
+	}
+}
+EXPORT_SYMBOL(pci_disable_ptm);
+
 void pci_save_ptm_state(struct pci_dev *dev)
 {
 	u16 ptm = dev->ptm_cap;
@@ -151,18 +166,8 @@  void pci_ptm_init(struct pci_dev *dev)
 		pci_enable_ptm(dev, NULL);
 }
 
-/**
- * pci_enable_ptm() - Enable Precision Time Measurement
- * @dev: PCI device
- * @granularity: pointer to return granularity
- *
- * Enable Precision Time Measurement for @dev.  If successful and
- * @granularity is non-NULL, return the Effective Granularity.
- *
- * Return: zero if successful, or -EINVAL if @dev lacks a PTM Capability or
- * is not a PTM Root and lacks an upstream path of PTM-enabled devices.
- */
-int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
+/* Enable PTM in the Control register if possible */
+static int __pci_enable_ptm(struct pci_dev *dev)
 {
 	u16 ptm = dev->ptm_cap;
 	struct pci_dev *ups;
@@ -191,8 +196,29 @@  int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
 		ctrl |= PCI_PTM_CTRL_ROOT;
 
 	pci_write_config_dword(dev, ptm + PCI_PTM_CTRL, ctrl);
+	return 0;
+}
+
+/**
+ * pci_enable_ptm() - Enable Precision Time Measurement
+ * @dev: PCI device
+ * @granularity: pointer to return granularity
+ *
+ * Enable Precision Time Measurement for @dev.  If successful and
+ * @granularity is non-NULL, return the Effective Granularity.
+ *
+ * Return: zero if successful, or -EINVAL if @dev lacks a PTM Capability or
+ * is not a PTM Root and lacks an upstream path of PTM-enabled devices.
+ */
+int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
+{
+	int rc;
+
+	rc = __pci_enable_ptm(dev);
+	if (rc)
+		return rc;
+
 	dev->ptm_enabled = 1;
-
 	pci_ptm_info(dev);
 
 	if (granularity)
@@ -201,6 +227,23 @@  int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
 }
 EXPORT_SYMBOL(pci_enable_ptm);
 
+/*
+ * Disable PTM, but preserve dev->ptm_enabled so we silently re-enable it on
+ * resume if necessary.
+ */
+void pci_suspend_ptm(struct pci_dev *dev)
+{
+	if (dev->ptm_enabled)
+		__pci_disable_ptm(dev);
+}
+
+/* If PTM was enabled before suspend, re-enable it when resuming */
+void pci_resume_ptm(struct pci_dev *dev)
+{
+	if (dev->ptm_enabled)
+		__pci_enable_ptm(dev);
+}
+
 bool pcie_ptm_enabled(struct pci_dev *dev)
 {
 	if (!dev)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 54be939023a3..cb5f796e3319 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1678,10 +1678,12 @@  bool pci_ats_disabled(void);
 
 #ifdef CONFIG_PCIE_PTM
 int pci_enable_ptm(struct pci_dev *dev, u8 *granularity);
+void pci_disable_ptm(struct pci_dev *dev);
 bool pcie_ptm_enabled(struct pci_dev *dev);
 #else
 static inline int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
 { return -EINVAL; }
+static inline void pci_disable_ptm(struct pci_dev *dev) { }
 static inline bool pcie_ptm_enabled(struct pci_dev *dev)
 { return false; }
 #endif