Hi Lorenzo,
On Tue, Mar 01, 2016 at 02:44:08PM +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 PCI_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
> PCI_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@xxxxxxx>
> Acked-by: Will Deacon <will.deacon@xxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: David Daney <david.daney@xxxxxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> ---
> drivers/pci/host/pci-host-generic.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c
> index 1652bc7..e529825 100644
> --- a/drivers/pci/host/pci-host-generic.c
> +++ b/drivers/pci/host/pci-host-generic.c
> @@ -252,7 +252,10 @@ 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);
>
The next patch removes the arm and arm64 pcibios_enable_device()
implementations, which implies that arm and arm64 only need the generic
version, which simply calls pci_enable_resources(). That assumes r->parent
is set.
After this patch, we'll call pci_bus_claim_resources() for the
PCI_PROBE_ONLY case, and that sets r->parent for all the resources.
Where does r->parent get set in the non-PCI_PROBE_ONLY case? Obviously
that path *works*, because you're not changing anything there. I'd just
like to have a hint that makes this change more obvious.
Bjorn
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