linux-kernel - Re: [Linux-kernel-mentees] [PATCH v2 01/11] PCI: Move #define PCI_PM_* lines to drivers/pci/pci.h

Open Source and information security mailing list archives

Date:   Mon, 29 Jul 2019 16:44:05 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Kelsey Skunberg <skunberg.kelsey@...il.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [Linux-kernel-mentees] [PATCH v2 01/11] PCI: Move #define
 PCI_PM_* lines to drivers/pci/pci.h

[+to Rafael, author of commits mentioned below]

On Wed, Jul 24, 2019 at 05:38:38PM -0600, Kelsey Skunberg wrote:
> The #define PCI_PM_* lines are only used within drivers/pci/ and they do
> not need to be seen by the rest of the kernel. Move #define PCI_* to
> drivers/pci/pci.h
> 
> Signed-off-by: Kelsey Skunberg <skunberg.kelsey@...il.com>
> ---
>  drivers/pci/pci.h   | 5 +++++
>  include/linux/pci.h | 5 -----
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 1be03a97cb92..708413632429 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -39,6 +39,11 @@ int pci_probe_reset_function(struct pci_dev *dev);
>  int pci_bridge_secondary_bus_reset(struct pci_dev *dev);
>  int pci_bus_error_reset(struct pci_dev *dev);
>  
> +#define PCI_PM_D2_DELAY         200
> +#define PCI_PM_D3_WAIT          10
> +#define PCI_PM_D3COLD_WAIT      100
> +#define PCI_PM_BUS_WAIT         50

Unrelated to *this* patch, but while reviewing, I noticed this a few
lines below:

  static inline void pci_wakeup_event(struct pci_dev *dev)
  {
    /* Wait 100 ms before the system can be put into a sleep state. */
    pm_wakeup_event(&dev->dev, 100);
  }

I'm curious about what this 100ms is and whether it's related to
something in the PCIe spec.  E.g., is this another way of writing
PCI_PM_D3COLD_WAIT?

This constant was added to drivers/pci/pci.c as PCI_WAKEUP_COOLDOWN by
c125e96f0444 ("PM: Make it possible to avoid races between wakeup and
system sleep") and then moved to drivers/pci/pci.h and the name
removed by b6e335aeeb11 ("PCI/PM: Use pm_wakeup_event() directly for
reporting wakeup events").

>  /**
>   * struct pci_platform_pm_ops - Firmware PM callbacks
>   *
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 9e700d9f9f28..238449460210 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -145,11 +145,6 @@ static inline const char *pci_power_name(pci_power_t state)
>  	return pci_power_names[1 + (__force int) state];
>  }
>  
> -#define PCI_PM_D2_DELAY		200
> -#define PCI_PM_D3_WAIT		10
> -#define PCI_PM_D3COLD_WAIT	100
> -#define PCI_PM_BUS_WAIT		50
> -
>  /**
>   * typedef pci_channel_state_t
>   *
> -- 
> 2.20.1
> 
> _______________________________________________
> Linux-kernel-mentees mailing list
> Linux-kernel-mentees@...ts.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

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