[PATCH v1 22/25] PCI: tegra: Remove top-level resource from hierarchy

Bjorn Helgaas
2016-06-06T23:07:28Z

41534e53786d ("PCI: tegra: Implement a proper resource hierarchy") did two
things:

1) It added a top-level resource that encloses all resources declared in
the DT description, including registers and bridge apertures, and

2) It requested the bridge apertures, which means the PCI core can track
the resources used by PCI devices below the bridge.

The latter is necessary, but the former is questionable because there's no
guarantee that the bridge registers and the apertures are contiguous. In
this example:

# cat /proc/iomem
00000000-3fffffff : /pcie-controller@00003000
00000000-00000fff : /pcie-controller@00003000/pci@1,0
00003000-000037ff : pads
00003800-000039ff : afi
10000000-1fffffff : cs

the resource tree claims that [mem 0x00003a00-0x0fffffff] is consumed by
/pcie-controller@00003000, but it's not mentioned in the DT, and it might
actually be used by other devices.

Remove the top-level resource so we don't claim more than the device
actually consumes.

This reintroduces the problem that we can't match the resources, e.g.,
"pads", "afi", "cs", etc., to the DT device. I think this should be solved
by having the DT core request all resources of all devices in the DT (it
does not do that today). If a driver claims the device, it can request the
resources it uses. For example:

# cat /proc/iomem
00000000-00000fff : /pcie-controller@00003000
00000000-00000fff : /pcie-controller@00003000/pci@1,0
00003000-000037ff : /pcie-controller@00003000
00003000-000037ff : pads
00003800-000039ff : /pcie-controller@00003000
00003800-000039ff : afi
10000000-1fffffff : /pcie-controller@00003000
10000000-1fffffff : cs
...

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
drivers/pci/host/pci-tegra.c | 23 +++--------------------
1 file changed, 3 insertions(+), 20 deletions(-)

diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
index c388468..920a899 100644
--- a/drivers/pci/host/pci-tegra.c
+++ b/drivers/pci/host/pci-tegra.c
@@ -274,7 +274,6 @@ struct tegra_pcie {
struct list_head buses;
struct resource *cs;

- struct resource all;
struct resource io;
struct resource pio;
struct resource mem;
@@ -623,7 +622,7 @@ static int tegra_pcie_setup(int nr, struct pci_sys_data *sys)
sys->mem_offset = pcie->offset.mem;
sys->io_offset = pcie->offset.io;

- err = devm_request_resource(pcie->dev, &pcie->all, &pcie->io);
+ err = devm_request_resource(pcie->dev, &iomem_resource, &pcie->io);
if (err < 0)
return err;

@@ -631,11 +630,11 @@ static int tegra_pcie_setup(int nr, struct pci_sys_data *sys)
if (err < 0)
return err;

- err = devm_request_resource(pcie->dev, &pcie->all, &pcie->mem);
+ err = devm_request_resource(pcie->dev, &iomem_resource, &pcie->mem);
if (err < 0)
return err;

- err = devm_request_resource(pcie->dev, &pcie->all, &pcie->prefetch);
+ err = devm_request_resource(pcie->dev, &iomem_resource, &pcie->prefetch);
if (err)
return err;

@@ -1822,12 +1821,6 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *pcie)
struct resource res;
int err;

- memset(&pcie->all, 0, sizeof(pcie->all));
- pcie->all.flags = IORESOURCE_MEM;
- pcie->all.name = np->full_name;
- pcie->all.start = ~0;
- pcie->all.end = 0;
-
if (of_pci_range_parser_init(&parser, np)) {
dev_err(pcie->dev, "missing \"ranges\" property\n");
return -EINVAL;
@@ -1880,18 +1873,8 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *pcie)
}
break;
}
-
- if (res.start <= pcie->all.start)
- pcie->all.start = res.start;
-
- if (res.end >= pcie->all.end)
- pcie->all.end = res.end;
}

- err = devm_request_resource(pcie->dev, &iomem_resource, &pcie->all);
- if (err < 0)
- return err;
-
err = of_pci_parse_bus_range(np, &pcie->busn);
if (err < 0) {
dev_err(pcie->dev, "failed to parse ranges property: %d\n",