[PATCH v2 2/5] powerpc/pci: Create pci_dn on demand

[Sam Bobroff]

Hi Sergey,

On Thu, Sep 06, 2018 at 02:57:49PM +0300, Sergey Miroshnichenko wrote:
> The pci_dn structures can be created not only from DT, but also
> directly from newly discovered PCIe devices, so allocate them
> dynamically.
> 
> Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko at yadro.com>
> ---
>  arch/powerpc/kernel/pci_dn.c | 76 ++++++++++++++++++++++++++++--------
>  1 file changed, 59 insertions(+), 17 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/pci_dn.c b/arch/powerpc/kernel/pci_dn.c
> index ab147a1909c8..48ec16407835 100644
> --- a/arch/powerpc/kernel/pci_dn.c
> +++ b/arch/powerpc/kernel/pci_dn.c
> @@ -33,6 +33,8 @@
>  #include <asm/firmware.h>
>  #include <asm/eeh.h>
>  
> +static struct pci_dn *create_pdn(struct pci_dev *pdev, struct pci_dn *parent);
> +
>  /*
>   * The function is used to find the firmware data of one
>   * specific PCI device, which is attached to the indicated
> @@ -58,6 +60,9 @@ static struct pci_dn *pci_bus_to_pdn(struct pci_bus *bus)
>  		pbus = pbus->parent;
>  	}
>  
> +	if (!pbus->self && !pci_is_root_bus(pbus))
> +		return NULL;
> +
>  	/*
>  	 * Except virtual bus, all PCI buses should
>  	 * have device nodes.
> @@ -65,13 +70,15 @@ static struct pci_dn *pci_bus_to_pdn(struct pci_bus *bus)
>  	dn = pci_bus_to_OF_node(pbus);
>  	pdn = dn ? PCI_DN(dn) : NULL;
>  
> +	if (!pdn && pbus->self)
> +		pdn = pbus->self->dev.archdata.pci_data;
> +
>  	return pdn;
>  }
>  
>  struct pci_dn *pci_get_pdn_by_devfn(struct pci_bus *bus,
>  				    int devfn)
>  {
> -	struct device_node *dn = NULL;
>  	struct pci_dn *parent, *pdn;
>  	struct pci_dev *pdev = NULL;
>  
> @@ -80,17 +87,10 @@ struct pci_dn *pci_get_pdn_by_devfn(struct pci_bus *bus,
>  		if (pdev->devfn == devfn) {
>  			if (pdev->dev.archdata.pci_data)
>  				return pdev->dev.archdata.pci_data;
> -
> -			dn = pci_device_to_OF_node(pdev);
>  			break;
>  		}
>  	}
>  
> -	/* Fast path: fetch from device node */
> -	pdn = dn ? PCI_DN(dn) : NULL;
> -	if (pdn)
> -		return pdn;
> -

Why is it necessary to remove the above fast-path?

>  	/* Slow path: fetch from firmware data hierarchy */
>  	parent = pci_bus_to_pdn(bus);
>  	if (!parent)
> @@ -128,16 +128,9 @@ struct pci_dn *pci_get_pdn(struct pci_dev *pdev)
>  	if (!parent)
>  		return NULL;
>  
> -	list_for_each_entry(pdn, &parent->child_list, list) {
> -		if (pdn->busno == pdev->bus->number &&
> -		    pdn->devfn == pdev->devfn)
> -			return pdn;
> -	}

Could you explain why the above block was removed? Is it now impossible
for it to find a pdn?

> -
> -	return NULL;
> +	return create_pdn(pdev, parent);
>  }
>  
> -#ifdef CONFIG_PCI_IOV
>  static struct pci_dn *add_one_dev_pci_data(struct pci_dn *parent,
>  					   int vf_index,
>  					   int busno, int devfn)
> @@ -156,7 +149,9 @@ static struct pci_dn *add_one_dev_pci_data(struct pci_dn *parent,
>  	pdn->parent = parent;
>  	pdn->busno = busno;
>  	pdn->devfn = devfn;
> +	#ifdef CONFIG_PCI_IOV
>  	pdn->vf_index = vf_index;
> +	#endif /* CONFIG_PCI_IOV */
>  	pdn->pe_number = IODA_INVALID_PE;
>  	INIT_LIST_HEAD(&pdn->child_list);
>  	INIT_LIST_HEAD(&pdn->list);

I can see that this change allows you to re-use this to set up a pdn in
create_pdn(). Perhaps you should refactor pci_add_device_node_info() to
use it as well, now that it's possible?

> @@ -164,7 +159,54 @@ static struct pci_dn *add_one_dev_pci_data(struct pci_dn *parent,
>  
>  	return pdn;
>  }
> -#endif
> +
> +static struct pci_dn *create_pdn(struct pci_dev *pdev, struct pci_dn *parent)
> +{
> +	struct pci_dn *pdn = NULL;
> +
> +	pdn = add_one_dev_pci_data(parent, 0, pdev->bus->number, pdev->devfn);
> +	dev_info(&pdev->dev, "Create a new pdn for devfn %2x\n", pdev->devfn / 8);
> +
> +	if (pdn) {
> +		#ifdef CONFIG_EEH
> +		struct eeh_dev *edev;
> +		#endif /* CONFIG_EEH */
> +		u32 class_code;
> +		u16 device_id;
> +		u16 vendor_id;
> +
> +		#ifdef CONFIG_EEH
> +		edev = eeh_dev_init(pdn);
> +		if (!edev) {
> +			kfree(pdn);
> +			dev_err(&pdev->dev, "%s: Failed to allocate edev\n", __func__);
> +			return NULL;
> +		}
> +		#endif /* CONFIG_EEH */
> +
> +		pdn->busno = pdev->bus->busn_res.start;

It seems strange that pdn->busno is set by the call to
add_one_dev_pci_data() above (to pdev->bus->number) and then overwritten
here with a different value. Should add_one_dev_pci_data() use
pdev->bus->busn_res.start and this line be removed?

> +
> +		pci_bus_read_config_word(pdev->bus, pdev->devfn,
> +					 PCI_VENDOR_ID, &vendor_id);
> +		pdn->vendor_id = vendor_id;
> +
> +		pci_bus_read_config_word(pdev->bus, pdev->devfn,
> +					 PCI_DEVICE_ID, &device_id);
> +		pdn->device_id = device_id;
> +
> +		pci_bus_read_config_dword(pdev->bus, pdev->devfn,
> +					  PCI_CLASS_REVISION, &class_code);
> +		class_code >>= 8;
> +		pdn->class_code = class_code;
> +
> +		pdn->pci_ext_config_space = 0;
> +		pdev->dev.archdata.pci_data = pdn;
> +	} else {
> +		dev_err(&pdev->dev, "%s: Failed to allocate pdn\n", __func__);
> +	}
> +
> +	return pdn;
> +}


>  
>  struct pci_dn *add_dev_pci_data(struct pci_dev *pdev)
>  {
> -- 
> 2.17.1
> 
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