linux-kernel - Re: [PATCH v2 2/8] PCI/MSI: Add hooks to populate the msi

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Date:	Tue, 13 Jan 2015 20:34:02 +0800
From:	Yijing Wang <wangyijing@...wei.com>
To:	Marc Zyngier <marc.zyngier@....com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jiang Liu <jiang.liu@...ux.intel.com>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	<linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
Subject: Re: [PATCH v2 2/8] PCI/MSI: Add hooks to populate the msi_domain
 field

>  static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
>  					   struct pci_dev *bridge, int busnr)
>  {
> @@ -713,6 +727,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
>  	bridge->subordinate = child;
>  
>  add_dev:
> +	pci_set_bus_msi_domain(child);
>  	ret = device_register(&child->dev);
>  	WARN_ON(ret < 0);
>  
> @@ -1507,6 +1522,17 @@ static void pci_init_capabilities(struct pci_dev *dev)
>  	pci_enable_acs(dev);
>  }
>  
> +static void pci_set_msi_domain(struct pci_dev *dev)
> +{
> +	/*
> +	 * If no domain has been set through the pcibios callback,
> +	 * inherit the default from the bus device.
> +	 */
> +	if (!dev_get_msi_domain(&dev->dev))
> +		dev_set_msi_domain(&dev->dev,
> +				   dev_get_msi_domain(&dev->bus->dev));
> +}

Hi Marc, now we have two ways to associate the pci_dev and msi_domain, right ?

1. associate pci_dev and msi_domain in pcibios_add_device() like x86.

2. Inherit msi_domain from pci_dev->bus.

My question is if all pci devices inherit msi_domain from the pci_bus,
so all pci devices under same pci host bridge have the same msi_domain assigned by
weak pcibios_set_phb_msi_domain(). So why not save the pci host bridge specific
msi_domain in pci_host_bridge. Then pci devices could inherit the msi_domain from
its pci host bridge directly, no need to involve pci bus in the assignment.

If I misunderstood, please let me know, :)

Thanks!
Yijing.

> +
>  void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
>  {
>  	int ret;
> @@ -1547,6 +1573,9 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
>  	ret = pcibios_add_device(dev);
>  	WARN_ON(ret < 0);
>  
> +	/* Setup MSI irq domain */
> +	pci_set_msi_domain(dev);
> +
>  	/* Notifier could use PCI capabilities */
>  	dev->match_driver = false;
>  	ret = device_add(&dev->dev);
> @@ -1937,6 +1966,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>  	b->bridge = get_device(&bridge->dev);
>  	device_enable_async_suspend(b->bridge);
>  	pci_set_bus_of_node(b);
> +	pci_set_bus_msi_domain(b);
>  
>  	if (!parent)
>  		set_dev_node(b->bridge, pcibus_to_node(b));
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 360a966..13c65ab 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1640,6 +1640,7 @@ 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);
> +void pcibios_set_phb_msi_domain(struct pci_bus *bus);
>  
>  #ifdef CONFIG_HIBERNATE_CALLBACKS
>  extern struct dev_pm_ops pcibios_pm_ops;
> 


-- 
Thanks!
Yijing

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