Message-ID: <5579E74A.3000808@amd.com>
Date: Thu, 11 Jun 2015 14:53:46 -0500
From: Suravee Suthikulanit <suravee.suthikulpanit@amd.com>
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To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        <linux-kernel@vger.kernel.org>, <linux-pci@vger.kernel.org>
CC: Ralf Baechle <ralf@linux-mips.org>,
        "James E.J. Bottomley" <jejb@parisc-linux.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Richard Henderson <rth@twiddle.net>,
        "Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
        David Howells <dhowells@redhat.com>,
        Russell King <linux@arm.linux.org.uk>, Tony Luck <tony.luck@intel.com>,
        "David S. Miller" <davem@davemloft.net>,
        Ingo Molnar <mingo@redhat.com>, Guenter Roeck <linux@roeck-us.net>,
        Michal Simek <monstr@monstr.eu>, Chris Zankel <chris@zankel.net>,
        Arnd Bergmann <arnd@arndb.de>, Krzysztof Halasa <khalasa@piap.pl>,
        Phil Edworthy <phil.edworthy@renesas.com>,
        Jason Gunthorpe <jgunthorpe@obsidianresearch.com>,
        Jingoo Han <jg1.han@samsung.com>,
        "Lucas Stach" <l.stach@pengutronix.de>,
        Simon Horman <horms@verge.net.au>,
        "Minghuan Lian" <minghuan.Lian@freescale.com>,
        Murali Karicheri <m-karicheri2@ti.com>,
        Tanmay Inamdar <tinamdar@apm.com>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
        Will Deacon <will.deacon@arm.com>,
        Jayachandran C <jchandra@broadcom.com>
Subject: Re: [RFC/RFT PATCH v2] PCI: move pci_read_bridge_bases to the generic
 PCI layer
References: <1433840506-20083-1-git-send-email-lorenzo.pieralisi@arm.com>
In-Reply-To: <1433840506-20083-1-git-send-email-lorenzo.pieralisi@arm.com>
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For ARM64 PROBE_ONLY and non-PROBE_ONLY modes:

Reviewed and Tested-by: Suravee Suthikulpanit 
<Suravee.Suthikulpanit@amd.com>

Please see minor comments below.

On 6/9/2015 4:01 AM, 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.
>
> In order to validate the resource hierarchy as soon as the resources
> themselves are probed (ie read from the bridge), this patch also adds
> code to pci_read_bridge_bases that claims the bridge resources, so that
> they are validated and inserted in the resource hierarchy as soon as
> the bridge bases are probed.
>
> 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>
> ---
> 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              | 26 ++++++++++++++++++++++++++
>   12 files changed, 29 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 0d05406..722dd5f 100644
> --- a/arch/powerpc/kernel/pci-common.c
> +++ b/arch/powerpc/kernel/pci-common.c
> @@ -1043,13 +1043,7 @@ 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 6675a7a..1913e1b 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -332,6 +332,21 @@ static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
>   	}
>   }
>
> +static void pci_claim_bridge_resources(struct pci_bus *bus)
> +{
> +	struct pci_dev *dev = bus->self;
> +	int idx;
> +
> +	for (idx = PCI_BRIDGE_RESOURCES; idx < PCI_NUM_RESOURCES; idx++) {
> +		struct resource *r = &dev->resource[idx];
> +
> +		if (!r->flags || r->parent)
> +			continue;
> +
> +		pci_claim_bridge_resource(dev, idx);
> +	}
> +}
> +

Nitpicking: Since pci_claim_bridge_resources() is small, and only called 
once from pci_read_brdige_bases(), should we just put the loop inside 
the function?

>   static void pci_read_bridge_io(struct pci_bus *child)
>   {
>   	struct pci_dev *dev = child->self;
> @@ -479,6 +494,8 @@ void pci_read_bridge_bases(struct pci_bus *child)
>   			}
>   		}
>   	}
> +
> +	pci_claim_bridge_resources(child);
>   }
>
>   static struct pci_bus *pci_alloc_bus(struct pci_bus *parent)
> @@ -826,6 +843,11 @@ 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",
> @@ -886,6 +908,10 @@ 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 {
>   			/*
>


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