On receiving a PTM Request from a downstream device, if PTM is disabled
on the root port, as per PCIe specification, such request would cause
an Unsupported Request error. So disable PTM for any downstream devices.
PTM state needs to be saved before disabling it to be restored later.
set ptm_enabled from 'struct pci_dev' to 0 in pci_ptm_disable() and
it is used in pci_save_state() before saving PTM state to avoid
double save.
Fixes: a697f072f5da ("PCI: Disable PTM during suspend to save power")
Signed-off-by: Rajvi Jingar <[email protected]>
Suggested-by: David E. Box <[email protected]>
---
v1 -> v2: add Fixes tag in commit message
v2 -> v3: move changelog after "---" marker
v3 -> v4: add "---" marker after changelog
v4 -> v5: move pci_disable_ptm() out of the pci_dev->state_saved check.
disable PTM for all devices, not just root ports.
v5 -> v6: move pci_disable_ptm() to pci_pm_suspend()
set pci_dev->ptm_enabled to 0 in pci_ptm_disable() and it is
used in pci_save_state() before saving PTM state to avoid
double save.
---
drivers/pci/pci-driver.c | 21 ++++++++++++++++++++-
drivers/pci/pci.c | 26 +++++++++++---------------
drivers/pci/pcie/ptm.c | 1 +
3 files changed, 32 insertions(+), 16 deletions(-)
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 1f64de3e5280..db4d7835d7ae 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -803,14 +803,33 @@ static int pci_pm_suspend(struct device *dev)
pci_dev_adjust_pme(pci_dev);
}
+ /*
+ * If a PTM Requester is put in a low-power state, a PTM Responder
+ * upstream from it may also be put in a low-power state. Putting a
+ * Port in D1, D2, or D3hot does not prohibit it from sending or
+ * responding to PTM Requests. We want to disable PTM on Responders
+ * when they are in a low-power state. Per 6.21.3, a PTM Requester
+ * must not be enabled when the upstream PTM Responder is disabled.
+ * Therefore, we must disable all PTM on all downstream PTM
+ * Requesters before disabling it on the PTM Responder, e.g., a Root
+ * Port.
+ *
+ * Also, to restore the PTM state, it needs to be saved before
+ * disabling it for all devices.
+ */
+ pci_save_ptm_state(pci_dev);
+ pci_disable_ptm(pci_dev);
+
if (pm->suspend) {
pci_power_t prev = pci_dev->current_state;
int error;
error = pm->suspend(dev);
suspend_report_result(dev, pm->suspend, error);
- if (error)
+ if (error) {
+ pci_restore_ptm_state(pci_dev);
return error;
+ }
if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0
&& pci_dev->current_state != PCI_UNKNOWN) {
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index cfaf40a540a8..0df9b783621e 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1669,7 +1669,13 @@ int pci_save_state(struct pci_dev *dev)
pci_save_ltr_state(dev);
pci_save_dpc_state(dev);
pci_save_aer_state(dev);
- pci_save_ptm_state(dev);
+ /*
+ * PCI PM core disables PTM during suspend and saves PTM state before
+ * that to be able to restore the ptm state restored later. So PCI core
+ * needs this check to avoid double save.
+ */
+ if (dev->ptm_enabled)
+ pci_save_ptm_state(dev);
return pci_save_vc_state(dev);
}
EXPORT_SYMBOL(pci_save_state);
@@ -2710,24 +2716,12 @@ 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;
}
@@ -2775,8 +2769,10 @@ int pci_finish_runtime_suspend(struct pci_dev *dev)
* 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)
+ if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) {
+ pci_save_ptm_state(dev);
pci_disable_ptm(dev);
+ }
__pci_enable_wake(dev, target_state, pci_dev_run_wake(dev));
diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
index 368a254e3124..746e29779c27 100644
--- a/drivers/pci/pcie/ptm.c
+++ b/drivers/pci/pcie/ptm.c
@@ -44,6 +44,7 @@ void pci_disable_ptm(struct pci_dev *dev)
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);
+ dev->ptm_enabled = 0;
}
void pci_save_ptm_state(struct pci_dev *dev)
--
2.25.1
Hi Rajvi,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on helgaas-pci/next]
[also build test ERROR on linus/master v5.19-rc1 next-20220608]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/intel-lab-lkp/linux/commits/Rajvi-Jingar/PCI-PM-refactor-pci_pm_suspend_noirq/20220608-092412
base: https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git next
config: i386-randconfig-a001 (https://download.01.org/0day-ci/archive/20220609/[email protected]/config)
compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
reproduce (this is a W=1 build):
# https://github.com/intel-lab-lkp/linux/commit/1bf4649d5fa01aa9d1ce606461791344adfaa2ab
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Rajvi-Jingar/PCI-PM-refactor-pci_pm_suspend_noirq/20220608-092412
git checkout 1bf4649d5fa01aa9d1ce606461791344adfaa2ab
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <[email protected]>
All errors (new ones prefixed by >>):
drivers/pci/pci.c: In function 'pci_save_state':
>> drivers/pci/pci.c:1677:18: error: 'struct pci_dev' has no member named 'ptm_enabled'; did you mean 'ats_enabled'?
1677 | if (dev->ptm_enabled)
| ^~~~~~~~~~~
| ats_enabled
vim +1677 drivers/pci/pci.c
1644
1645 /**
1646 * pci_save_state - save the PCI configuration space of a device before
1647 * suspending
1648 * @dev: PCI device that we're dealing with
1649 */
1650 int pci_save_state(struct pci_dev *dev)
1651 {
1652 int i;
1653 /* XXX: 100% dword access ok here? */
1654 for (i = 0; i < 16; i++) {
1655 pci_read_config_dword(dev, i * 4, &dev->saved_config_space[i]);
1656 pci_dbg(dev, "saving config space at offset %#x (reading %#x)\n",
1657 i * 4, dev->saved_config_space[i]);
1658 }
1659 dev->state_saved = true;
1660
1661 i = pci_save_pcie_state(dev);
1662 if (i != 0)
1663 return i;
1664
1665 i = pci_save_pcix_state(dev);
1666 if (i != 0)
1667 return i;
1668
1669 pci_save_ltr_state(dev);
1670 pci_save_dpc_state(dev);
1671 pci_save_aer_state(dev);
1672 /*
1673 * PCI PM core disables PTM during suspend and saves PTM state before
1674 * that to be able to restore the ptm state restored later. So PCI core
1675 * needs this check to avoid double save.
1676 */
> 1677 if (dev->ptm_enabled)
1678 pci_save_ptm_state(dev);
1679 return pci_save_vc_state(dev);
1680 }
1681 EXPORT_SYMBOL(pci_save_state);
1682
--
0-DAY CI Kernel Test Service
https://01.org/lkp
On Thu, Jun 09, 2022 at 02:14:32AM +0800, kernel test robot wrote:
> Hi Rajvi,
>
> Thank you for the patch! Yet something to improve:
>
> [auto build test ERROR on helgaas-pci/next]
> [also build test ERROR on linus/master v5.19-rc1 next-20220608]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]
I'll wait for the v7 to fix the warning.
At the same time, please capitalize the subject lines per convention,
and also the "set ptm_enabled" in 2/2 commit log.
> url: https://github.com/intel-lab-lkp/linux/commits/Rajvi-Jingar/PCI-PM-refactor-pci_pm_suspend_noirq/20220608-092412
> base: https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git next
> config: i386-randconfig-a001 (https://download.01.org/0day-ci/archive/20220609/[email protected]/config)
> compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
> reproduce (this is a W=1 build):
> # https://github.com/intel-lab-lkp/linux/commit/1bf4649d5fa01aa9d1ce606461791344adfaa2ab
> git remote add linux-review https://github.com/intel-lab-lkp/linux
> git fetch --no-tags linux-review Rajvi-Jingar/PCI-PM-refactor-pci_pm_suspend_noirq/20220608-092412
> git checkout 1bf4649d5fa01aa9d1ce606461791344adfaa2ab
> # save the config file
> mkdir build_dir && cp config build_dir/.config
> make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <[email protected]>
>
> All errors (new ones prefixed by >>):
>
> drivers/pci/pci.c: In function 'pci_save_state':
> >> drivers/pci/pci.c:1677:18: error: 'struct pci_dev' has no member named 'ptm_enabled'; did you mean 'ats_enabled'?
> 1677 | if (dev->ptm_enabled)
> | ^~~~~~~~~~~
> | ats_enabled
>
>
> vim +1677 drivers/pci/pci.c
>
> 1644
> 1645 /**
> 1646 * pci_save_state - save the PCI configuration space of a device before
> 1647 * suspending
> 1648 * @dev: PCI device that we're dealing with
> 1649 */
> 1650 int pci_save_state(struct pci_dev *dev)
> 1651 {
> 1652 int i;
> 1653 /* XXX: 100% dword access ok here? */
> 1654 for (i = 0; i < 16; i++) {
> 1655 pci_read_config_dword(dev, i * 4, &dev->saved_config_space[i]);
> 1656 pci_dbg(dev, "saving config space at offset %#x (reading %#x)\n",
> 1657 i * 4, dev->saved_config_space[i]);
> 1658 }
> 1659 dev->state_saved = true;
> 1660
> 1661 i = pci_save_pcie_state(dev);
> 1662 if (i != 0)
> 1663 return i;
> 1664
> 1665 i = pci_save_pcix_state(dev);
> 1666 if (i != 0)
> 1667 return i;
> 1668
> 1669 pci_save_ltr_state(dev);
> 1670 pci_save_dpc_state(dev);
> 1671 pci_save_aer_state(dev);
> 1672 /*
> 1673 * PCI PM core disables PTM during suspend and saves PTM state before
> 1674 * that to be able to restore the ptm state restored later. So PCI core
> 1675 * needs this check to avoid double save.
> 1676 */
> > 1677 if (dev->ptm_enabled)
> 1678 pci_save_ptm_state(dev);
> 1679 return pci_save_vc_state(dev);
> 1680 }
> 1681 EXPORT_SYMBOL(pci_save_state);
> 1682
>
> --
> 0-DAY CI Kernel Test Service
> https://01.org/lkp