Re: [RFC PATCH] PCI: Enable pci bridge when it is needed

[Yijing Wang]

I think it's cool! Now we enable bridge in various places, this is a headache.

hi, yinghai, in this patch, enable bridges depend on the driver call pci_enable_device() explicitly.
I was a little worried If there has some devices don't have some drivers bound, but used by system.
like ioapic, these devices maybe implemented as pci device, but no pci drivers bind, also, maybe they
won't call pci_enable_device() explicity. So if they are under the pci bridge, no one will enable the bridge
for them.

Thanks!
Yijing.

On 2013/4/27 9:09, Yinghai Lu wrote:
> Current we enable bridges after bus scan and assign resources.
> and it is spreaded a lot of places.
> 
> We can move it to where pci device is enabled, and need
> to go up to root bus and enable bridge one by one down to pci
> dev.
> 
> So that will delay enable bridge late as needed bassis,
> also kill one inconsistent between boot path and hotplug
> path in acpi_pci_root_add().
> 
> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
> 
> ---
>  arch/arm/kernel/bios32.c           |    5 -----
>  arch/m68k/platform/coldfire/pci.c  |    1 -
>  arch/mips/pci/pci.c                |    1 -
>  arch/sh/drivers/pci/pci.c          |    1 -
>  drivers/acpi/pci_root.c            |    4 ----
>  drivers/parisc/lba_pci.c           |    1 -
>  drivers/pci/bus.c                  |   19 -------------------
>  drivers/pci/hotplug/acpiphp_glue.c |    1 -
>  drivers/pci/pci.c                  |   20 ++++++++++++++++++++
>  drivers/pci/probe.c                |    1 -
>  drivers/pci/setup-bus.c            |   11 +++--------
>  drivers/pcmcia/cardbus.c           |    1 -
>  include/linux/pci.h                |    1 -
>  13 files changed, 23 insertions(+), 44 deletions(-)
> 
> Index: linux-2.6/arch/arm/kernel/bios32.c
> ===================================================================
> --- linux-2.6.orig/arch/arm/kernel/bios32.c
> +++ linux-2.6/arch/arm/kernel/bios32.c
> @@ -523,11 +523,6 @@ void pci_common_init(struct hw_pci *hw)
>  			 * Assign resources.
>  			 */
>  			pci_bus_assign_resources(bus);
> -
> -			/*
> -			 * Enable bridges
> -			 */
> -			pci_enable_bridges(bus);
>  		}
>  
>  		/*
> Index: linux-2.6/arch/m68k/platform/coldfire/pci.c
> ===================================================================
> --- linux-2.6.orig/arch/m68k/platform/coldfire/pci.c
> +++ linux-2.6/arch/m68k/platform/coldfire/pci.c
> @@ -319,7 +319,6 @@ static int __init mcf_pci_init(void)
>  	pci_fixup_irqs(pci_common_swizzle, mcf_pci_map_irq);
>  	pci_bus_size_bridges(rootbus);
>  	pci_bus_assign_resources(rootbus);
> -	pci_enable_bridges(rootbus);
>  	pci_bus_add_devices(rootbus);
>  	return 0;
>  }
> Index: linux-2.6/arch/mips/pci/pci.c
> ===================================================================
> --- linux-2.6.orig/arch/mips/pci/pci.c
> +++ linux-2.6/arch/mips/pci/pci.c
> @@ -113,7 +113,6 @@ static void pcibios_scanbus(struct pci_c
>  		if (!pci_has_flag(PCI_PROBE_ONLY)) {
>  			pci_bus_size_bridges(bus);
>  			pci_bus_assign_resources(bus);
> -			pci_enable_bridges(bus);
>  		}
>  	}
>  }
> Index: linux-2.6/arch/sh/drivers/pci/pci.c
> ===================================================================
> --- linux-2.6.orig/arch/sh/drivers/pci/pci.c
> +++ linux-2.6/arch/sh/drivers/pci/pci.c
> @@ -69,7 +69,6 @@ static void pcibios_scanbus(struct pci_c
>  
>  		pci_bus_size_bridges(bus);
>  		pci_bus_assign_resources(bus);
> -		pci_enable_bridges(bus);
>  	} else {
>  		pci_free_resource_list(&resources);
>  	}
> Index: linux-2.6/drivers/acpi/pci_root.c
> ===================================================================
> --- linux-2.6.orig/drivers/acpi/pci_root.c
> +++ linux-2.6/drivers/acpi/pci_root.c
> @@ -538,10 +538,6 @@ static int acpi_pci_root_add(struct acpi
>  		pci_assign_unassigned_bus_resources(root->bus);
>  	}
>  
> -	/* need to after hot-added ioapic is registered */
> -	if (system_state != SYSTEM_BOOTING)
> -		pci_enable_bridges(root->bus);
> -
>  	pci_bus_add_devices(root->bus);
>  	return 1;
>  
> Index: linux-2.6/drivers/parisc/lba_pci.c
> ===================================================================
> --- linux-2.6.orig/drivers/parisc/lba_pci.c
> +++ linux-2.6/drivers/parisc/lba_pci.c
> @@ -1533,7 +1533,6 @@ lba_driver_probe(struct parisc_device *d
>  		lba_dump_res(&lba_dev->hba.lmmio_space, 2);
>  #endif
>  	}
> -	pci_enable_bridges(lba_bus);
>  
>  	/*
>  	** Once PCI register ops has walked the bus, access to config
> Index: linux-2.6/drivers/pci/bus.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/bus.c
> +++ linux-2.6/drivers/pci/bus.c
> @@ -215,24 +215,6 @@ void pci_bus_add_devices(const struct pc
>  	}
>  }
>  
> -void pci_enable_bridges(struct pci_bus *bus)
> -{
> -	struct pci_dev *dev;
> -	int retval;
> -
> -	list_for_each_entry(dev, &bus->devices, bus_list) {
> -		if (dev->subordinate) {
> -			if (!pci_is_enabled(dev)) {
> -				retval = pci_enable_device(dev);
> -				if (retval)
> -					dev_err(&dev->dev, "Error enabling bridge (%d), continuing\n", retval);
> -				pci_set_master(dev);
> -			}
> -			pci_enable_bridges(dev->subordinate);
> -		}
> -	}
> -}
> -
>  /** pci_walk_bus - walk devices on/under bus, calling callback.
>   *  @top      bus whose devices should be walked
>   *  @cb       callback to be called for each device found
> @@ -285,4 +267,3 @@ EXPORT_SYMBOL_GPL(pci_walk_bus);
>  EXPORT_SYMBOL(pci_bus_alloc_resource);
>  EXPORT_SYMBOL_GPL(pci_bus_add_device);
>  EXPORT_SYMBOL(pci_bus_add_devices);
> -EXPORT_SYMBOL(pci_enable_bridges);
> Index: linux-2.6/drivers/pci/hotplug/acpiphp_glue.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/hotplug/acpiphp_glue.c
> +++ linux-2.6/drivers/pci/hotplug/acpiphp_glue.c
> @@ -704,7 +704,6 @@ static int __ref enable_device(struct ac
>  	acpiphp_sanitize_bus(bus);
>  	acpiphp_set_hpp_values(bus);
>  	acpiphp_set_acpi_region(slot);
> -	pci_enable_bridges(bus);
>  
>  	list_for_each_entry(dev, &bus->devices, bus_list) {
>  		/* Assume that newly added devices are powered on already. */
> Index: linux-2.6/drivers/pci/pci.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/pci.c
> +++ linux-2.6/drivers/pci/pci.c
> @@ -1145,6 +1145,24 @@ int pci_reenable_device(struct pci_dev *
>  	return 0;
>  }
>  
> +static void pci_enable_bridge(struct pci_dev *dev)
> +{
> +	int retval;
> +
> +	if (!dev)
> +		return;
> +
> +	pci_enable_bridge(dev->bus->self);
> +
> +	if (pci_is_enabled(dev))
> +		return;
> +	retval = pci_enable_device(dev);
> +	if (retval)
> +		dev_err(&dev->dev, "Error enabling bridge (%d), continuing\n",
> +			retval);
> +	pci_set_master(dev);
> +}
> +
>  static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
>  {
>  	int err;
> @@ -1165,6 +1183,8 @@ static int pci_enable_device_flags(struc
>  	if (atomic_inc_return(&dev->enable_cnt) > 1)
>  		return 0;		/* already enabled */
>  
> +	pci_enable_bridge(dev->bus->self);
> +
>  	/* only skip sriov related */
>  	for (i = 0; i <= PCI_ROM_RESOURCE; i++)
>  		if (dev->resource[i].flags & flags)
> Index: linux-2.6/drivers/pci/probe.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/probe.c
> +++ linux-2.6/drivers/pci/probe.c
> @@ -1949,7 +1949,6 @@ unsigned int __ref pci_rescan_bus(struct
>  
>  	max = pci_scan_child_bus(bus);
>  	pci_assign_unassigned_bus_resources(bus);
> -	pci_enable_bridges(bus);
>  	pci_bus_add_devices(bus);
>  
>  	return max;
> Index: linux-2.6/drivers/pci/setup-bus.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/setup-bus.c
> +++ linux-2.6/drivers/pci/setup-bus.c
> @@ -1435,7 +1435,7 @@ again:
>  
>  	/* any device complain? */
>  	if (list_empty(&fail_head))
> -		goto enable_and_dump;
> +		goto dump;
>  
>  	if (tried_times >= pci_try_num) {
>  		if (pci_realloc_enable == undefined)
> @@ -1444,7 +1444,7 @@ again:
>  			printk(KERN_INFO "Automatically enabled pci realloc, if you have problem, try booting with pci=realloc=off\n");
>  
>  		free_list(&fail_head);
> -		goto enable_and_dump;
> +		goto dump;
>  	}
>  
>  	printk(KERN_DEBUG "PCI: No. %d try to assign unassigned res\n",
> @@ -1478,11 +1478,7 @@ again:
>  
>  	goto again;
>  
> -enable_and_dump:
> -	/* Depth last, update the hardware. */
> -	list_for_each_entry(bus, &pci_root_buses, node)
> -		pci_enable_bridges(bus);
> -
> +dump:
>  	/* dump the resource on buses */
>  	list_for_each_entry(bus, &pci_root_buses, node)
>  		pci_bus_dump_resources(bus);
> @@ -1548,7 +1544,6 @@ enable_all:
>  	if (retval)
>  		dev_err(&bridge->dev, "Error reenabling bridge (%d)\n", retval);
>  	pci_set_master(bridge);
> -	pci_enable_bridges(parent);
>  }
>  EXPORT_SYMBOL_GPL(pci_assign_unassigned_bridge_resources);
>  
> Index: linux-2.6/drivers/pcmcia/cardbus.c
> ===================================================================
> --- linux-2.6.orig/drivers/pcmcia/cardbus.c
> +++ linux-2.6/drivers/pcmcia/cardbus.c
> @@ -91,7 +91,6 @@ int __ref cb_alloc(struct pcmcia_socket
>  	if (s->tune_bridge)
>  		s->tune_bridge(s, bus);
>  
> -	pci_enable_bridges(bus);
>  	pci_bus_add_devices(bus);
>  
>  	return 0;
> Index: linux-2.6/include/linux/pci.h
> ===================================================================
> --- linux-2.6.orig/include/linux/pci.h
> +++ linux-2.6/include/linux/pci.h
> @@ -1040,7 +1040,6 @@ int __must_check pci_bus_alloc_resource(
>  						  resource_size_t,
>  						  resource_size_t),
>  			void *alignf_data);
> -void pci_enable_bridges(struct pci_bus *bus);
>  
>  /* Proper probing supporting hot-pluggable devices */
>  int __must_check __pci_register_driver(struct pci_driver *, struct module *,
> 
> .
> 


-- 
Thanks!
Yijing

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