linux-kernel - Re: [PATCH v3 07/10] PCI/PTM: Add suspend/resume

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Date:   Wed, 7 Sep 2022 08:30:47 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Rajvi Jingar <rajvi.jingar@...ux.intel.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Koba Ko <koba.ko@...onical.com>,
        "David E . Box" <david.e.box@...ux.intel.com>,
        Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        linux-pci@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v3 07/10] PCI/PTM: Add suspend/resume

On Tue, Sep 06, 2022 at 05:23:48PM -0500, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@...gle.com>
> 

I think it is good to explain here why this patch is needed. Even if
just one sentence.

> ---
>  drivers/pci/pci.c      |  4 ++--
>  drivers/pci/pci.h      |  4 ++++
>  drivers/pci/pcie/ptm.c | 15 +++++++++++++++
>  3 files changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 95bc329e74c0..83818f81577d 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -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));
>  
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 91a465460d0f..ce4a277e3f41 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -507,9 +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_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_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 *);
> diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
> index 4a9f045126ca..8ac844212436 100644
> --- a/drivers/pci/pcie/ptm.c
> +++ b/drivers/pci/pcie/ptm.c
> @@ -198,6 +198,21 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
>  }
>  EXPORT_SYMBOL(pci_enable_ptm);
>  
> +/*
> + * Disable PTM, but leave dev->ptm_enabled so we silently re-enable it on
> + * resume.
> + */

Proper kernel-doc for both.

> +void pci_suspend_ptm(struct pci_dev *dev)
> +{
> +	__pci_disable_ptm(dev);
> +}
> +
> +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)
> -- 
> 2.25.1