linux-kernel - Re: [PATCH v10 09/10] PCI: Assign unassigned bus resources in pci_scan_root

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Message-ID: <5412C75F.30207@amd.com>
Date:	Fri, 12 Sep 2014 05:13:51 -0500
From:	Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:	Liviu Dudau <Liviu.Dudau@....com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Arnd Bergmann <arnd@...db.de>,
	Rob Herring <robh+dt@...nel.org>,
	"Jason Gunthorpe" <jgunthorpe@...idianresearch.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Catalin Marinas <catalin.marinas@....com>,
	"Will Deacon" <Will.Deacon@....com>,
	Russell King <linux@....linux.org.uk>,
	linux-pci <linux-pci@...r.kernel.org>,
	Linus Walleij <linus.walleij@...aro.org>
CC:	Tanmay Inamdar <tinamdar@....com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Sinan Kaya <okaya@...eaurora.org>,
	Jingoo Han <jg1.han@...sung.com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	linux-arch <linux-arch@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Device Tree ML" <devicetree@...r.kernel.org>,
	LAKML <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v10 09/10] PCI: Assign unassigned bus resources in pci_scan_root_bus()

On 9/8/2014 8:54 AM, Liviu Dudau wrote:
> If the firmware has not assigned all the bus resources and
> we are not just probing the PCIe busses, it makes sense to
> assign the unassigned resources in pci_scan_root_bus().
>
> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Jason Gunthorpe <jgunthorpe@...idianresearch.com>
> Cc: Rob Herring <robh+dt@...nel.org>
> Signed-off-by: Liviu Dudau <Liviu.Dudau@....com>
> ---
>   drivers/pci/probe.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index ef891d2..508cf61 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1953,6 +1953,9 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
>   	if (!found)
>   		pci_bus_update_busn_res_end(b, max);
>
> +	if (!pci_has_flag(PCI_PROBE_ONLY))
> +		pci_assign_unassigned_bus_resources(b);
> +
>   	pci_bus_add_devices(b);
>   	return b;
>   }
>

Liviu,

Besides the check for PCI_PROBE_ONLY here, I think we also need to avoid calling
"pci_enable_resources()" in the "driver/pci/pci.c: pcibios_enable_device()" for
PCI_PROBE_ONLY mode since the resource is not assigned by Linux. Otherwise, the
"drivers/pci/setup-res.c: pci_enable_resource()" would fail w/ error:

     can't enable device: BAR ..... not assigned

Actually, in "arch/arm/kernel/bios32.c:", the weak "pcibios_enable_device()" function
also has the check for PCI_PROBE_ONLY mode before calling pci_enable_resources().

Thanks,

Suravee

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