From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Huang Ying <ying.huang@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>, linux-kernel@vger.kernel.org,
        linux-pci@vger.kernel.org, linux-pm@vger.kernel.org,
        stable@vger.kernel.org
Subject: Re: [BUGFIX] PCI/PM: Fix proc config reg access for D3cold and bridge suspending
Date: Thu, 25 Oct 2012 22:27:43 +0200
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On Thursday, October 25, 2012 09:36:03 AM Huang Ying wrote:
> In
> 
>   https://bugzilla.kernel.org/show_bug.cgi?id=48981
> 
> Peter reported that /proc/bus/pci/??/??.? does not works for 3.6.
> This is This is because the device configuration space registers will
> be not accessible if the corresponding parent bridge is suspended or
> the device is put into D3cold state.
> 
> This is the same as /sys/bus/pci/devices/0000:??:??.?/config access
> issue.  So the function used to solve sysfs issue is used to solve
> this issue.
> 
> Cc: stable@vger.kernel.org
> Reported-by: Peter <lekensteyn@gmail.com>
> Signed-off-by: Huang Ying <ying.huang@intel.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
>  drivers/pci/pci-sysfs.c |   34 ----------------------------------
>  drivers/pci/pci.c       |   32 ++++++++++++++++++++++++++++++++
>  drivers/pci/pci.h       |    2 ++
>  drivers/pci/proc.c      |    8 ++++++++
>  4 files changed, 42 insertions(+), 34 deletions(-)
> 
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -458,40 +458,6 @@ boot_vga_show(struct device *dev, struct
>  }
>  struct device_attribute vga_attr = __ATTR_RO(boot_vga);
>  
> -static void
> -pci_config_pm_runtime_get(struct pci_dev *pdev)
> -{
> -	struct device *dev = &pdev->dev;
> -	struct device *parent = dev->parent;
> -
> -	if (parent)
> -		pm_runtime_get_sync(parent);
> -	pm_runtime_get_noresume(dev);
> -	/*
> -	 * pdev->current_state is set to PCI_D3cold during suspending,
> -	 * so wait until suspending completes
> -	 */
> -	pm_runtime_barrier(dev);
> -	/*
> -	 * Only need to resume devices in D3cold, because config
> -	 * registers are still accessible for devices suspended but
> -	 * not in D3cold.
> -	 */
> -	if (pdev->current_state == PCI_D3cold)
> -		pm_runtime_resume(dev);
> -}
> -
> -static void
> -pci_config_pm_runtime_put(struct pci_dev *pdev)
> -{
> -	struct device *dev = &pdev->dev;
> -	struct device *parent = dev->parent;
> -
> -	pm_runtime_put(dev);
> -	if (parent)
> -		pm_runtime_put_sync(parent);
> -}
> -
>  static ssize_t
>  pci_read_config(struct file *filp, struct kobject *kobj,
>  		struct bin_attribute *bin_attr,
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1858,6 +1858,38 @@ bool pci_dev_run_wake(struct pci_dev *de
>  }
>  EXPORT_SYMBOL_GPL(pci_dev_run_wake);
>  
> +void pci_config_pm_runtime_get(struct pci_dev *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device *parent = dev->parent;
> +
> +	if (parent)
> +		pm_runtime_get_sync(parent);
> +	pm_runtime_get_noresume(dev);
> +	/*
> +	 * pdev->current_state is set to PCI_D3cold during suspending,
> +	 * so wait until suspending completes
> +	 */
> +	pm_runtime_barrier(dev);
> +	/*
> +	 * Only need to resume devices in D3cold, because config
> +	 * registers are still accessible for devices suspended but
> +	 * not in D3cold.
> +	 */
> +	if (pdev->current_state == PCI_D3cold)
> +		pm_runtime_resume(dev);
> +}
> +
> +void pci_config_pm_runtime_put(struct pci_dev *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device *parent = dev->parent;
> +
> +	pm_runtime_put(dev);
> +	if (parent)
> +		pm_runtime_put_sync(parent);
> +}
> +
>  /**
>   * pci_pm_init - Initialize PM functions of given PCI device
>   * @dev: PCI device to handle.
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -72,6 +72,8 @@ extern void pci_disable_enabled_device(s
>  extern int pci_finish_runtime_suspend(struct pci_dev *dev);
>  extern int __pci_pme_wakeup(struct pci_dev *dev, void *ign);
>  extern void pci_wakeup_bus(struct pci_bus *bus);
> +extern void pci_config_pm_runtime_get(struct pci_dev *dev);
> +extern void pci_config_pm_runtime_put(struct pci_dev *dev);
>  extern void pci_pm_init(struct pci_dev *dev);
>  extern void platform_pci_wakeup_init(struct pci_dev *dev);
>  extern void pci_allocate_cap_save_buffers(struct pci_dev *dev);
> --- a/drivers/pci/proc.c
> +++ b/drivers/pci/proc.c
> @@ -76,6 +76,8 @@ proc_bus_pci_read(struct file *file, cha
>  	if (!access_ok(VERIFY_WRITE, buf, cnt))
>  		return -EINVAL;
>  
> +	pci_config_pm_runtime_get(dev);
> +
>  	if ((pos & 1) && cnt) {
>  		unsigned char val;
>  		pci_user_read_config_byte(dev, pos, &val);
> @@ -121,6 +123,8 @@ proc_bus_pci_read(struct file *file, cha
>  		cnt--;
>  	}
>  
> +	pci_config_pm_runtime_put(dev);
> +
>  	*ppos = pos;
>  	return nbytes;
>  }
> @@ -146,6 +150,8 @@ proc_bus_pci_write(struct file *file, co
>  	if (!access_ok(VERIFY_READ, buf, cnt))
>  		return -EINVAL;
>  
> +	pci_config_pm_runtime_get(dev);
> +
>  	if ((pos & 1) && cnt) {
>  		unsigned char val;
>  		__get_user(val, buf);
> @@ -191,6 +197,8 @@ proc_bus_pci_write(struct file *file, co
>  		cnt--;
>  	}
>  
> +	pci_config_pm_runtime_put(dev);
> +
>  	*ppos = pos;
>  	i_size_write(ino, dp->size);
>  	return nbytes;
> --
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> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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