[PATCH 1/2] PCI/PM: refactor pci_pm_suspend_noirq()

[PATCH 1/2] PCI/PM: refactor pci_pm_suspend_noirq()

[Rajvi Jingar]

The state of the device is saved during pci_pm_suspend_noirq(), if it
has not already been saved, regardless of the skip_bus_pm flag value. So
skip_bus_pm check is removed before saving the device state.

Signed-off-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 This patch is a resend of https://lkml.org/lkml/2022/6/8/1462
---
 drivers/pci/pci-driver.c | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 49238ddd39ee..1f64de3e5280 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -867,20 +867,14 @@ static int pci_pm_suspend_noirq(struct device *dev)
 		}
 	}
 
-	if (pci_dev->skip_bus_pm) {
+	if (!pci_dev->state_saved) {
+		pci_save_state(pci_dev);
 		/*
-		 * Either the device is a bridge with a child in D0 below it, or
-		 * the function is running for the second time in a row without
-		 * going through full resume, which is possible only during
-		 * suspend-to-idle in a spurious wakeup case.  The device should
-		 * be in D0 at this point, but if it is a bridge, it may be
-		 * necessary to save its state.
+		 * If the device is a bridge with a child in D0 below it, it needs to
+		 * stay in D0, so check skip_bus_pm to avoid putting it into a
+		 * low-power state in that case.
 		 */
-		if (!pci_dev->state_saved)
-			pci_save_state(pci_dev);
-	} else if (!pci_dev->state_saved) {
-		pci_save_state(pci_dev);
-		if (pci_power_manageable(pci_dev))
+		if (!pci_dev->skip_bus_pm && pci_power_manageable(pci_dev))
 			pci_prepare_to_sleep(pci_dev);
 	}
 
-- 
2.25.1

[PATCH 2/2] PCI/PTM: fix in pci_disable_ptm()

[Rajvi Jingar]

Set ptm_enabled from 'struct pci_dev' to 0 in pci_ptm_disable() to
save the disabled PTM state for the device.

Fixes: a697f072f5da ("PCI: Disable PTM during suspend to save power")
Signed-off-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
---
 drivers/pci/pcie/ptm.c | 1 +
 1 file changed, 1 insertion(+)

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

Re: [PATCH 2/2] PCI/PTM: fix in pci_disable_ptm()

[Rafael J. Wysocki]

On Thu, Jul 7, 2022 at 7:22 PM Rajvi Jingar
<rajvi.jingar@linux.intel.com> wrote:
>
> Set ptm_enabled from 'struct pci_dev' to 0 in pci_ptm_disable() to

I would set "Clear" here instead of "Set", but moreover ->

> save the disabled PTM state for the device.
>
> Fixes: a697f072f5da ("PCI: Disable PTM during suspend to save power")
> Signed-off-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
> ---
>  drivers/pci/pcie/ptm.c | 1 +
>  1 file changed, 1 insertion(+)
>
> 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;

-> I don't think that this is going to work without setting
dev->ptm_enabled in pci_restore_ptm_state() if the restored state
turns out to be "enabled".

>  }
>
>  void pci_save_ptm_state(struct pci_dev *dev)
> --

Re: [PATCH 2/2] PCI/PTM: fix in pci_disable_ptm()

[Rafael J. Wysocki]

On Thu, Jul 7, 2022 at 8:27 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Thu, Jul 7, 2022 at 7:22 PM Rajvi Jingar
> <rajvi.jingar@linux.intel.com> wrote:
> >
> > Set ptm_enabled from 'struct pci_dev' to 0 in pci_ptm_disable() to
>
> I would set "Clear" here instead of "Set", but moreover ->

s/set/say/ sorry.

> > save the disabled PTM state for the device.
> >
> > Fixes: a697f072f5da ("PCI: Disable PTM during suspend to save power")
> > Signed-off-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
> > ---
> >  drivers/pci/pcie/ptm.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > 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;
>
> -> I don't think that this is going to work without setting
> dev->ptm_enabled in pci_restore_ptm_state() if the restored state
> turns out to be "enabled".

And arguably, this function doesn't need to do anything if
dev->ptm_enabled is 0 already and this is the only check it needs to
do, because dev->ptm_enabled will only be set for PCIe devices that
have PTM.

> >  }
> >
> >  void pci_save_ptm_state(struct pci_dev *dev)
> > --