linux-kernel - Re: [Patch v2 1/4] PCI: Add hooks to allocate/free IRQ resources when binding/unbinding driver

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Date:	Fri, 5 Jun 2015 16:17:32 -0500
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Jiang Liu <jiang.liu@...ux.intel.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	"Rafael J . Wysocki" <rjw@...ysocki.net>,
	LKML <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org,
	linux-acpi@...r.kernel.org, "x86 @ kernel . org" <x86@...nel.org>
Subject: Re: [Patch v2 1/4] PCI: Add hooks to allocate/free IRQ resources
 when binding/unbinding driver

On Tue, Jun 02, 2015 at 10:49:16AM +0800, Jiang Liu wrote:
> Add two hook points pcibios_{alloc|free}_irq() into PCI core, which will
> be called when binding/unbinding PCI device drivers. Then PCI arch code
> may hook into these two points to allocate IRQ resources on demand and
> free them when not used anymore.
> 
> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
> ---
>  drivers/pci/pci-driver.c |   26 ++++++++++++++++++++------
>  include/linux/pci.h      |    2 ++
>  2 files changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 3cb2210de553..450ad36ffc77 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -388,18 +388,31 @@ static int __pci_device_probe(struct pci_driver *drv, struct pci_dev *pci_dev)
>  	return error;
>  }
>  
> +int __weak pcibios_alloc_irq(struct pci_dev *dev)
> +{
> +	return dev->irq;

Based on your usage, pcibios_alloc_irq() returns either zero or a negative
errno.  So I think you should return 0 here.

> +}
> +
> +void __weak pcibios_free_irq(struct pci_dev *dev)
> +{
> +}
> +
>  static int pci_device_probe(struct device *dev)
>  {
> -	int error = 0;
> -	struct pci_driver *drv;
> -	struct pci_dev *pci_dev;
> +	int error;
> +	struct pci_dev *pci_dev = to_pci_dev(dev);
> +	struct pci_driver *drv = to_pci_driver(dev->driver);
> +
> +	error = pcibios_alloc_irq(pci_dev);
> +	if (error < 0)
> +		return error;
>  
> -	drv = to_pci_driver(dev->driver);
> -	pci_dev = to_pci_dev(dev);
>  	pci_dev_get(pci_dev);
>  	error = __pci_device_probe(drv, pci_dev);
> -	if (error)
> +	if (error) {
> +		pcibios_free_irq(pci_dev);
>  		pci_dev_put(pci_dev);
> +	}
>  
>  	return error;
>  }
> @@ -415,6 +428,7 @@ static int pci_device_remove(struct device *dev)
>  			drv->remove(pci_dev);
>  			pm_runtime_put_noidle(dev);
>  		}
> +		pcibios_free_irq(pci_dev);
>  		pci_dev->driver = NULL;
>  	}
>  
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 353db8dc4c6e..f50d16a04abc 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1656,6 +1656,8 @@ int pcibios_set_pcie_reset_state(struct pci_dev *dev,
>  int pcibios_add_device(struct pci_dev *dev);
>  void pcibios_release_device(struct pci_dev *dev);
>  void pcibios_penalize_isa_irq(int irq, int active);
> +int pcibios_alloc_irq(struct pci_dev *dev);
> +void pcibios_free_irq(struct pci_dev *dev);
>  
>  #ifdef CONFIG_HIBERNATE_CALLBACKS
>  extern struct dev_pm_ops pcibios_pm_ops;
> -- 
> 1.7.10.4
> 
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