linux-kernel - Re: [PATCH 1/12] PCI PM: Add function for checking PME status of devices

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Date:	Wed, 6 Jan 2010 13:46:37 -0800
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Matthew Garrett <mjg@...hat.com>, Len Brown <lenb@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Alan Stern <stern@...land.harvard.edu>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	Oliver Neukum <oliver@...kum.org>,
	Bjorn Helgaas <bjorn.helgaas@...com>,
	Shaohua Li <shaohua.li@...el.com>,
	Francois Romieu <romieu@...zoreil.com>
Subject: Re: [PATCH 1/12] PCI PM: Add function for checking PME status of
 devices

On Sun, 27 Dec 2009 20:59:06 +0100
"Rafael J. Wysocki" <rjw@...k.pl> wrote:

> From: Rafael J. Wysocki <rjw@...k.pl>
> 
> Add function pci_check_pme_status() that will check the PME status
> bit of given device and clear it along with the PME enable bit.  It
> will be necessary for PCI run-time power management.
> 
> Based on a patch from Shaohua Li <shaohua.li@...el.com>
> 
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> ---
>  drivers/pci/pci.c |   35 +++++++++++++++++++++++++++++++++++
>  drivers/pci/pci.h |    1 +
>  2 files changed, 36 insertions(+)
> 
> Index: linux-2.6/drivers/pci/pci.h
> ===================================================================
> --- linux-2.6.orig/drivers/pci/pci.h
> +++ linux-2.6/drivers/pci/pci.h
> @@ -49,6 +49,7 @@ struct pci_platform_pm_ops {
>  extern int pci_set_platform_pm(struct pci_platform_pm_ops *ops);
>  extern void pci_update_current_state(struct pci_dev *dev,
> pci_power_t state); extern void pci_disable_enabled_device(struct
> pci_dev *dev); +extern bool pci_check_pme_status(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);
> Index: linux-2.6/drivers/pci/pci.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/pci.c
> +++ linux-2.6/drivers/pci/pci.c
> @@ -1180,6 +1180,41 @@ int pci_set_pcie_reset_state(struct pci_
>  }
>  
>  /**
> + * pci_check_pme_status - Check if given device has generated PME.
> + * @dev: Device to check.
> + *
> + * Check the PME status of the device and if set, clear it and clear
> PME enable
> + * (if set).  Return 'true' if PME status and PME enable were both
> set or
> + * 'false' otherwise.
> + */
> +bool pci_check_pme_status(struct pci_dev *dev)
> +{
> +	int pmcsr_pos;
> +	u16 pmcsr;
> +	bool ret = false;
> +
> +	if (!dev->pm_cap)
> +		return false;
> +
> +	pmcsr_pos = dev->pm_cap + PCI_PM_CTRL;
> +	pci_read_config_word(dev, pmcsr_pos, &pmcsr);
> +	if (!(pmcsr & PCI_PM_CTRL_PME_STATUS))
> +		return false;
> +
> +	/* Clear PME status. */
> +	pmcsr |= PCI_PM_CTRL_PME_STATUS;
> +	if (pmcsr & PCI_PM_CTRL_PME_ENABLE) {
> +		/* Disable PME to avoid interrupt flood. */
> +		pmcsr &= ~PCI_PM_CTRL_PME_ENABLE;
> +		ret = true;
> +	}
> +
> +	pci_write_config_word(dev, pmcsr_pos, pmcsr);
> +
> +	return ret;
> +}
> +
> +/**
>   * pci_pme_capable - check the capability of PCI device to generate
> PME#
>   * @dev: PCI device to handle.
>   * @state: PCI state from which device will issue PME#.
> 
> 

Looks fine to me; would be especially nice if we could somehow
communicate that this function was ack'ing any outstanding PME event in
the function name too.

-- 
Jesse Barnes, Intel Open Source Technology Center
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