[2/3] drivers: pci: host-generic: claim bus resources on PROBE_ONLY set-ups

The PCI host generic driver does not reassign bus resources on systems
that require the BARs set-up to be immutable (ie PROBE_ONLY) since
that would trigger system failures. Nonetheless, PCI bus resources
allocated to PCI bridge and devices must be claimed in order to be
validated and inserted in the kernel resource tree, but the current
driver omits the resources claiming and relies on arch specific kludges
to prevent probing failure (ie preventing resources enablement on
PROBE_ONLY systems).

This patch adds code to the PCI host generic driver that correctly
claims bus resources upon probe on systems that are required to
prevent reassignment after bus enumeration, so that the allocated
resources can be enabled successfully upon PCI device drivers probing,
without resorting to arch back-ends workarounds.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Daney <david.daney@cavium.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/host/pci-host-generic.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

On Tue, Nov 17, 2015 at 05:03:57PM +0000, Lorenzo Pieralisi wrote:
> The PCI host generic driver does not reassign bus resources on systems
> that require the BARs set-up to be immutable (ie PROBE_ONLY) since
> that would trigger system failures. Nonetheless, PCI bus resources
> allocated to PCI bridge and devices must be claimed in order to be
> validated and inserted in the kernel resource tree, but the current
> driver omits the resources claiming and relies on arch specific kludges
> to prevent probing failure (ie preventing resources enablement on
> PROBE_ONLY systems).
> 
> This patch adds code to the PCI host generic driver that correctly
> claims bus resources upon probe on systems that are required to
> prevent reassignment after bus enumeration, so that the allocated
> resources can be enabled successfully upon PCI device drivers probing,
> without resorting to arch back-ends workarounds.
> 
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: David Daney <david.daney@cavium.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> ---
>  drivers/pci/host/pci-host-generic.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

Assuming patch one is accepted, then this looks fine to me:

  Acked-by: Will Deacon <will.deacon@arm.com>

Will

> diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c
> index 5434c90..c62d13f 100644
> --- a/drivers/pci/host/pci-host-generic.c
> +++ b/drivers/pci/host/pci-host-generic.c
> @@ -261,7 +261,10 @@ static int gen_pci_probe(struct platform_device *pdev)
>  
>  	pci_fixup_irqs(pci_common_swizzle, of_irq_parse_and_map_pci);
>  
> -	if (!pci_has_flag(PCI_PROBE_ONLY)) {
> +
> +	if (pci_has_flag(PCI_PROBE_ONLY)) {
> +		pci_bus_claim_resources(bus);
> +	} else {
>  		pci_bus_size_bridges(bus);
>  		pci_bus_assign_resources(bus);
>  
> -- 
> 2.5.1
> 
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