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Merge branch 'pci/ptm'

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- Save/restore Precision Time Measurement Capability for suspend/resume
  (David E. Box)

- Disable PTM during suspend to save power (David E. Box)

* pci/ptm:
  PCI: Disable PTM during suspend to save power
  PCI/PTM: Save/restore Precision Time Measurement Capability for suspend/resume
This commit is contained in:
Bjorn Helgaas 2020-12-15 15:11:09 -06:00
commit 72b3a644bb
3 changed files with 96 additions and 1 deletions
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27
drivers/pci/pci.c
View File

@ -1561,6 +1561,7 @@ int pci_save_state(struct pci_dev *dev)
pci_save_aspm_l1ss_state(dev);
pci_save_dpc_state(dev);
pci_save_aer_state(dev);
pci_save_ptm_state(dev);
return pci_save_vc_state(dev);
}
EXPORT_SYMBOL(pci_save_state);
@ -1673,6 +1674,7 @@ void pci_restore_state(struct pci_dev *dev)
pci_restore_vc_state(dev);
pci_restore_rebar_state(dev);
pci_restore_dpc_state(dev);
pci_restore_ptm_state(dev);
pci_aer_clear_status(dev);
pci_restore_aer_state(dev);
@ -2602,12 +2604,24 @@ int pci_prepare_to_sleep(struct pci_dev *dev)
if (target_state == PCI_POWER_ERROR)
return -EIO;
/*
* There are systems (for example, Intel mobile chips since Coffee
* Lake) where the power drawn while suspended can be significantly
* reduced by disabling PTM on PCIe root ports as this allows the
* port to enter a lower-power PM state and the SoC to reach a
* lower-power idle state as a whole.
*/
if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
pci_disable_ptm(dev);
pci_enable_wake(dev, target_state, wakeup);
error = pci_set_power_state(dev, target_state);
if (error)
if (error) {
pci_enable_wake(dev, target_state, false);
pci_restore_ptm_state(dev);
}
return error;
}
@ -2645,12 +2659,23 @@ int pci_finish_runtime_suspend(struct pci_dev *dev)
dev->runtime_d3cold = target_state == PCI_D3cold;
/*
* There are systems (for example, Intel mobile chips since Coffee
* Lake) where the power drawn while suspended can be significantly
* reduced by disabling PTM on PCIe root ports as this allows the
* port to enter a lower-power PM state and the SoC to reach a
* lower-power idle state as a whole.
*/
if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
pci_disable_ptm(dev);
__pci_enable_wake(dev, target_state, pci_dev_run_wake(dev));
error = pci_set_power_state(dev, target_state);
if (error) {
pci_enable_wake(dev, target_state, false);
pci_restore_ptm_state(dev);
dev->runtime_d3cold = false;
}

10
drivers/pci/pci.h
View File

@ -524,6 +524,16 @@ static inline int pci_iov_bus_range(struct pci_bus *bus)
#endif /* CONFIG_PCI_IOV */
#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);
#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) { }
#endif
unsigned long pci_cardbus_resource_alignment(struct resource *);
static inline resource_size_t pci_resource_alignment(struct pci_dev *dev,

60
drivers/pci/pcie/ptm.c
View File

@ -29,6 +29,64 @@ static void pci_ptm_info(struct pci_dev *dev)
dev->ptm_root ? " (root)" : "", clock_desc);
}
void pci_disable_ptm(struct pci_dev *dev)
{
int ptm;
u16 ctrl;
if (!pci_is_pcie(dev))
return;
ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
if (!ptm)
return;
pci_read_config_word(dev, ptm + PCI_PTM_CTRL, &ctrl);
ctrl &= ~(PCI_PTM_CTRL_ENABLE | PCI_PTM_CTRL_ROOT);
pci_write_config_word(dev, ptm + PCI_PTM_CTRL, ctrl);
}
void pci_save_ptm_state(struct pci_dev *dev)
{
int ptm;
struct pci_cap_saved_state *save_state;
u16 *cap;
if (!pci_is_pcie(dev))
return;
ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
if (!ptm)
return;
save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_PTM);
if (!save_state) {
pci_err(dev, "no suspend buffer for PTM\n");
return;
}
cap = (u16 *)&save_state->cap.data[0];
pci_read_config_word(dev, ptm + PCI_PTM_CTRL, cap);
}
void pci_restore_ptm_state(struct pci_dev *dev)
{
struct pci_cap_saved_state *save_state;
int ptm;
u16 *cap;
if (!pci_is_pcie(dev))
return;
save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_PTM);
ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
if (!save_state || !ptm)
return;
cap = (u16 *)&save_state->cap.data[0];
pci_write_config_word(dev, ptm + PCI_PTM_CTRL, *cap);
}
void pci_ptm_init(struct pci_dev *dev)
{
int pos;
@ -65,6 +123,8 @@ void pci_ptm_init(struct pci_dev *dev)
if (!pos)
return;
pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_PTM, sizeof(u16));
pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap);
local_clock = (cap & PCI_PTM_GRANULARITY_MASK) >> 8;