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PCI/PTM: Add pci_suspend_ptm() and pci_resume_ptm()

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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.

Link: https://lore.kernel.org/r/20220909202505.314195-5-helgaas@kernel.org
Tested-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
This commit is contained in:
Bjorn Helgaas 2022-09-09 15:25:00 -05:00
parent 118b9dfdc1
commit e8bdc5ea48
4 changed files with 65 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/pci/pci.c
View File

@ -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));

6
drivers/pci/pci.h
View File

@ -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 *);

71
drivers/pci/pcie/ptm.c
View File

@ -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);
dev->ptm_enabled = 1;
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)

2
include/linux/pci.h
View File

@ -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