* Re: [PATCH 1/2] PCI/PM: refactor pci_pm_suspend_noirq()
[not found] <20220224202937.2414867-1-rajvi.jingar@intel.com>
@ 2022-03-11 18:33 ` Rafael J. Wysocki
[not found] ` <20220224202937.2414867-2-rajvi.jingar@intel.com>
1 sibling, 0 replies; 2+ messages in thread
From: Rafael J. Wysocki @ 2022-03-11 18:33 UTC (permalink / raw)
To: Rajvi Jingar, bhelgaas; +Cc: david.e.box, linux-pci, linux-kernel
On 2/24/2022 9:29 PM, Rajvi Jingar wrote:
> 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@intel.com>
> Suggested-by: David E. Box <david.e.box@linux.intel.com>
> ---
> drivers/pci/pci-driver.c | 15 ++-------------
> 1 file changed, 2 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 588588cfda48..ac3f7e1676a9 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -834,20 +834,9 @@ static int pci_pm_suspend_noirq(struct device *dev)
> }
> }
>
> - if (pci_dev->skip_bus_pm) {
> - /*
> - * 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.
> - */
The comment is outdated, but the role of skip_bus_pm needs to be
explained. It only applies to the bridge with a child in D0 case now,
because the other one has gone away, so I would put a new comment before
the reworked check below.
> - if (!pci_dev->state_saved)
> - pci_save_state(pci_dev);
> - } else if (!pci_dev->state_saved) {
> + if (!pci_dev->state_saved) {
> pci_save_state(pci_dev);
> - if (pci_power_manageable(pci_dev))
For example:
/*
* 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->skip_bus_pm && pci_power_manageable(pci_dev))
> pci_prepare_to_sleep(pci_dev);
> }
>
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH 2/2] PCI/PM: Fix pci_pm_suspend_noirq() to disable PTM
[not found] ` <20220224202937.2414867-2-rajvi.jingar@intel.com>
@ 2022-03-11 18:38 ` Rafael J. Wysocki
0 siblings, 0 replies; 2+ messages in thread
From: Rafael J. Wysocki @ 2022-03-11 18:38 UTC (permalink / raw)
To: Rajvi Jingar, bhelgaas; +Cc: david.e.box, linux-pci, linux-kernel
On 2/24/2022 9:29 PM, Rajvi Jingar wrote:
> For the PCIe devices (like nvme) that do not go into D3 state still need to
> disable PTM on PCIe root ports to allow the port to enter a lower-power PM
> state and the SoC to reach a lower-power idle state as a whole. Move the
> pci_disable_ptm() out of pci_prepare_to_sleep() as this code path is not
> followed for devices that do not go into D3. This patch fixes the issue
> seen on Dell XPS 9300 with Ice Lake CPU and Dell Precision 5530 with Coffee
> Lake CPU platforms to get improved residency in low power idle states.
>
> Signed-off-by: Rajvi Jingar <rajvi.jingar@intel.com>
> Suggested-by: David E. Box <david.e.box@linux.intel.com>
I would add a Fixes tag pointing to the commit that introduced
pci_disable_ptm().
Otherwise I agree with this change:
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> drivers/pci/pci-driver.c | 11 +++++++++++
> drivers/pci/pci.c | 10 ----------
> 2 files changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index ac3f7e1676a9..8be3f81afdf6 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -836,6 +836,17 @@ static int pci_pm_suspend_noirq(struct device *dev)
>
> if (!pci_dev->state_saved) {
> pci_save_state(pci_dev);
> +
> + /*
> + * 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(pci_dev) == PCI_EXP_TYPE_ROOT_PORT)
> + pci_disable_ptm(pci_dev);
> +
> if (!pci_dev->skip_bus_pm && pci_power_manageable(pci_dev))
> pci_prepare_to_sleep(pci_dev);
> }
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 9ecce435fb3f..f8768672c064 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2660,16 +2660,6 @@ 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);
^ permalink raw reply [flat|nested] 2+ messages in thread
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[not found] <20220224202937.2414867-1-rajvi.jingar@intel.com>
2022-03-11 18:33 ` [PATCH 1/2] PCI/PM: refactor pci_pm_suspend_noirq() Rafael J. Wysocki
[not found] ` <20220224202937.2414867-2-rajvi.jingar@intel.com>
2022-03-11 18:38 ` [PATCH 2/2] PCI/PM: Fix pci_pm_suspend_noirq() to disable PTM Rafael J. Wysocki
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