Re: [RFT PATCH v3] PCI: move pci_read_bridge_bases to the generic PCI layer

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

Bjorn, Guenter,

On Thu, Jul 09, 2015 at 11:59:16AM +0100, Lorenzo Pieralisi wrote:
> When a PCI bus is scanned, upon PCI bridge detection the kernel
> has to read the bridge registers to set-up its resources so that
> the PCI resource hierarchy can be validated properly.
> 
> Most if not all architectures read PCI bridge registers in the
> pcibios_fixup_bus hook, that is called by the PCI generic layer
> whenever a PCI bus is scanned.
> 
> Since pci_read_bridge_bases is an arch agnostic operation (and it
> is carried out on all architectures) it can be moved to the generic
> PCI layer in order to consolidate code and remove the respective
> calls from the architectures back-ends.
> 
> The PCI_PROBE_ONLY flag is not checked before calling
> pci_read_bridge_buses in the generic layer since reading the bridge
> bases is not related to resources assignment; this implies that it
> can be carried out safely on PCI_PROBE_ONLY systems too and should
> not affect architectures (alpha, mips) that check the PCI_PROBE_ONLY
> flag before reading the bridge bases.
> 
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> Cc: James E.J. Bottomley <jejb@parisc-linux.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Richard Henderson <rth@twiddle.net>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: David Howells <dhowells@redhat.com>
> Cc: Russell King <linux@arm.linux.org.uk>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: Michal Simek <monstr@monstr.eu>
> Cc: Chris Zankel <chris@zankel.net>
> ---
> v2->v3:
> 
> - Dropped RFC status
> - Removed bridge resources claiming from pci_read_bridge_bases()

What do you want me to do with this patch ? I removed the resource
claiming - ie the only controversial bit, I can only test on
arm64, I would like to make some progress on this otherwise
I will have to add the bridge bases read to arm64 pcibios_fixup_bus()
and be done with this.

Thanks,
Lorenzo

> v2: https://lkml.org/lkml/2015/6/9/187
> 
> v1->v2:
> 
> - Moved pci_read_bridge_bases call to pci_scan_bridge to read bases before
>   scanning devices
> - Added bridge resources claiming
> 
> v1: https://lkml.org/lkml/2015/5/21/359
> 
>  arch/alpha/kernel/pci.c          | 7 +------
>  arch/frv/mb93090-mb00/pci-vdk.c  | 2 --
>  arch/ia64/pci/pci.c              | 1 -
>  arch/microblaze/pci/pci-common.c | 9 +--------
>  arch/mips/pci/pci.c              | 6 ------
>  arch/mn10300/unit-asb2305/pci.c  | 1 -
>  arch/powerpc/kernel/pci-common.c | 8 +-------
>  arch/x86/pci/common.c            | 1 -
>  arch/xtensa/kernel/pci.c         | 4 ----
>  drivers/parisc/dino.c            | 3 ---
>  drivers/parisc/lba_pci.c         | 1 -
>  drivers/pci/probe.c              | 9 +++++++++
>  12 files changed, 12 insertions(+), 40 deletions(-)
> 
> diff --git a/arch/alpha/kernel/pci.c b/arch/alpha/kernel/pci.c
> index 82f738e..cded02c 100644
> --- a/arch/alpha/kernel/pci.c
> +++ b/arch/alpha/kernel/pci.c
> @@ -242,12 +242,7 @@ pci_restore_srm_config(void)
>  
>  void pcibios_fixup_bus(struct pci_bus *bus)
>  {
> -	struct pci_dev *dev = bus->self;
> -
> -	if (pci_has_flag(PCI_PROBE_ONLY) && dev &&
> - 		   (dev->class >> 8) == PCI_CLASS_BRIDGE_PCI) {
> - 		pci_read_bridge_bases(bus);
> -	} 
> +	struct pci_dev *dev;
>  
>  	list_for_each_entry(dev, &bus->devices, bus_list) {
>  		pdev_save_srm_config(dev);
> diff --git a/arch/frv/mb93090-mb00/pci-vdk.c b/arch/frv/mb93090-mb00/pci-vdk.c
> index f211839..f9c86c4 100644
> --- a/arch/frv/mb93090-mb00/pci-vdk.c
> +++ b/arch/frv/mb93090-mb00/pci-vdk.c
> @@ -294,8 +294,6 @@ void pcibios_fixup_bus(struct pci_bus *bus)
>  	printk("### PCIBIOS_FIXUP_BUS(%d)\n",bus->number);
>  #endif
>  
> -	pci_read_bridge_bases(bus);
> -
>  	if (bus->number == 0) {
>  		struct pci_dev *dev;
>  		list_for_each_entry(dev, &bus->devices, bus_list) {
> diff --git a/arch/ia64/pci/pci.c b/arch/ia64/pci/pci.c
> index 7cc3be9..563228b 100644
> --- a/arch/ia64/pci/pci.c
> +++ b/arch/ia64/pci/pci.c
> @@ -534,7 +534,6 @@ void pcibios_fixup_bus(struct pci_bus *b)
>  	struct pci_dev *dev;
>  
>  	if (b->self) {
> -		pci_read_bridge_bases(b);
>  		pcibios_fixup_bridge_resources(b->self);
>  	}
>  	list_for_each_entry(dev, &b->devices, bus_list)
> diff --git a/arch/microblaze/pci/pci-common.c b/arch/microblaze/pci/pci-common.c
> index ae838ed..6b8b752 100644
> --- a/arch/microblaze/pci/pci-common.c
> +++ b/arch/microblaze/pci/pci-common.c
> @@ -863,14 +863,7 @@ void pcibios_setup_bus_devices(struct pci_bus *bus)
>  
>  void pcibios_fixup_bus(struct pci_bus *bus)
>  {
> -	/* When called from the generic PCI probe, read PCI<->PCI bridge
> -	 * bases. This is -not- called when generating the PCI tree from
> -	 * the OF device-tree.
> -	 */
> -	if (bus->self != NULL)
> -		pci_read_bridge_bases(bus);
> -
> -	/* Now fixup the bus bus */
> +	/* Fixup the bus */
>  	pcibios_setup_bus_self(bus);
>  
>  	/* Now fixup devices on that bus */
> diff --git a/arch/mips/pci/pci.c b/arch/mips/pci/pci.c
> index b8a0bf5..c6996cf 100644
> --- a/arch/mips/pci/pci.c
> +++ b/arch/mips/pci/pci.c
> @@ -311,12 +311,6 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
>  
>  void pcibios_fixup_bus(struct pci_bus *bus)
>  {
> -	struct pci_dev *dev = bus->self;
> -
> -	if (pci_has_flag(PCI_PROBE_ONLY) && dev &&
> -	    (dev->class >> 8) == PCI_CLASS_BRIDGE_PCI) {
> -		pci_read_bridge_bases(bus);
> -	}
>  }
>  
>  EXPORT_SYMBOL(PCIBIOS_MIN_IO);
> diff --git a/arch/mn10300/unit-asb2305/pci.c b/arch/mn10300/unit-asb2305/pci.c
> index 3dfe2d3..deaa893 100644
> --- a/arch/mn10300/unit-asb2305/pci.c
> +++ b/arch/mn10300/unit-asb2305/pci.c
> @@ -324,7 +324,6 @@ void pcibios_fixup_bus(struct pci_bus *bus)
>  	struct pci_dev *dev;
>  
>  	if (bus->self) {
> -		pci_read_bridge_bases(bus);
>  		pcibios_fixup_bridge_resources(bus->self);
>  	}
>  
> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
> index b9de34d..02c1d5d 100644
> --- a/arch/powerpc/kernel/pci-common.c
> +++ b/arch/powerpc/kernel/pci-common.c
> @@ -1044,13 +1044,7 @@ void pcibios_set_master(struct pci_dev *dev)
>  
>  void pcibios_fixup_bus(struct pci_bus *bus)
>  {
> -	/* When called from the generic PCI probe, read PCI<->PCI bridge
> -	 * bases. This is -not- called when generating the PCI tree from
> -	 * the OF device-tree.
> -	 */
> -	pci_read_bridge_bases(bus);
> -
> -	/* Now fixup the bus bus */
> +	/* Fixup the bus */
>  	pcibios_setup_bus_self(bus);
>  
>  	/* Now fixup devices on that bus */
> diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
> index 8fd6f44..3bff244 100644
> --- a/arch/x86/pci/common.c
> +++ b/arch/x86/pci/common.c
> @@ -166,7 +166,6 @@ void pcibios_fixup_bus(struct pci_bus *b)
>  {
>  	struct pci_dev *dev;
>  
> -	pci_read_bridge_bases(b);
>  	list_for_each_entry(dev, &b->devices, bus_list)
>  		pcibios_fixup_device_resources(dev);
>  }
> diff --git a/arch/xtensa/kernel/pci.c b/arch/xtensa/kernel/pci.c
> index b848cc3..d27b4dc 100644
> --- a/arch/xtensa/kernel/pci.c
> +++ b/arch/xtensa/kernel/pci.c
> @@ -210,10 +210,6 @@ subsys_initcall(pcibios_init);
>  
>  void pcibios_fixup_bus(struct pci_bus *bus)
>  {
> -	if (bus->parent) {
> -		/* This is a subordinate bridge */
> -		pci_read_bridge_bases(bus);
> -	}
>  }
>  
>  void pcibios_set_master(struct pci_dev *dev)
> diff --git a/drivers/parisc/dino.c b/drivers/parisc/dino.c
> index a0580af..baec33c 100644
> --- a/drivers/parisc/dino.c
> +++ b/drivers/parisc/dino.c
> @@ -560,9 +560,6 @@ dino_fixup_bus(struct pci_bus *bus)
>  	} else if (bus->parent) {
>  		int i;
>  
> -		pci_read_bridge_bases(bus);
> -
> -
>  		for(i = PCI_BRIDGE_RESOURCES; i < PCI_NUM_RESOURCES; i++) {
>  			if((bus->self->resource[i].flags & 
>  			    (IORESOURCE_IO | IORESOURCE_MEM)) == 0)
> diff --git a/drivers/parisc/lba_pci.c b/drivers/parisc/lba_pci.c
> index dceb9dd..901e1a3 100644
> --- a/drivers/parisc/lba_pci.c
> +++ b/drivers/parisc/lba_pci.c
> @@ -693,7 +693,6 @@ lba_fixup_bus(struct pci_bus *bus)
>  	if (bus->parent) {
>  		int i;
>  		/* PCI-PCI Bridge */
> -		pci_read_bridge_bases(bus);
>  		for (i = PCI_BRIDGE_RESOURCES; i < PCI_NUM_RESOURCES; i++)
>  			pci_claim_bridge_resource(bus->self, i);
>  	} else {
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index c80626f..de1c424 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -842,6 +842,11 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
>  			child->bridge_ctl = bctl;
>  		}
>  
> +		/*
> +		 * Read and initialize bridge resources.
> +		 */
> +		pci_read_bridge_bases(child);
> +
>  		cmax = pci_scan_child_bus(child);
>  		if (cmax > subordinate)
>  			dev_warn(&dev->dev, "bridge has subordinate %02x but max busn %02x\n",
> @@ -902,6 +907,10 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
>  
>  		if (!is_cardbus) {
>  			child->bridge_ctl = bctl;
> +			/*
> +			 * Read and initialize bridge resources.
> +			 */
> +			pci_read_bridge_bases(child);
>  			max = pci_scan_child_bus(child);
>  		} else {
>  			/*
> -- 
> 2.2.1
>