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SubjectRe: [BISECTED] Regression: Solidrun Clearfog Base won't boot since "PCI: mvebu: Only remap I/O space if configured"
Russell, Baruch, Jan,

On Thu, 13 Sep 2018 00:10:51 +0100, Russell King - ARM Linux wrote:

> It's probably the latter - the region is probably already mapped, that
> being the PCI IO region.
>
> The original driver was setup to call pci_ioremap_io() as the very
> last thing - and as the driver is non-removable, we were guaranteed
> to never tear down this mapping (which is sensible, it's published
> to userspace.)
>
> However, the current code calls pci_ioremap_io() much earlier, in
> a path where probe failures can occur. This breaks pci_ioremap_io()'s
> requirements - it must not be called more than once. So:
>
> ee1604381a37 ("PCI: mvebu: Only remap I/O space if configured")
>
> is basically incorrect - pci_ioremap_io() needs to move back to a
> place where it is only called in a path which will never fail.
> However, looking at the generic host bits, I'm not sure such a place
> exists in the new effort to make stuff more generic.

What about something like the below. I tested it, including the error
case by forcing an -EPROBE_DEFER. The new pci_unmap_io() is modeled
after pci_unmap_iospace(). Actually, I would prefer to use
pci_remap_iospace() and pci_unmap_iospace() but for now this API
doesn't allow overloading the memory type used for the mapping.

diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index 2cfbc531f63b..cee0e2be5ac7 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -185,6 +185,7 @@ static inline void pci_ioremap_set_mem_type(int mem_type) {}
#endif

extern int pci_ioremap_io(unsigned int offset, phys_addr_t phys_addr);
+extern void pci_unmap_io(unsigned int offset);

/*
* PCI configuration space mapping function.
diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index fc91205ff46c..f3a4df44bb27 100644
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -482,6 +482,14 @@ int pci_ioremap_io(unsigned int offset, phys_addr_t phys_addr)
}
EXPORT_SYMBOL_GPL(pci_ioremap_io);

+void pci_unmap_io(unsigned int offset)
+{
+ BUG_ON(offset + SZ_64K > IO_SPACE_LIMIT);
+
+ unmap_kernel_range(PCI_IO_VIRT_BASE + offset, SZ_64K);
+}
+EXPORT_SYMBOL_GPL(pci_unmap_io);
+
void __iomem *pci_remap_cfgspace(resource_size_t res_cookie, size_t size)
{
return arch_ioremap_caller(res_cookie, size, MT_UNCACHED,
diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
index 50eb0729385b..772cff19c2ce 100644
--- a/drivers/pci/controller/pci-mvebu.c
+++ b/drivers/pci/controller/pci-mvebu.c
@@ -1145,7 +1145,6 @@ static int mvebu_pcie_parse_request_resources(struct mvebu_pcie *pcie)
{
struct device *dev = &pcie->pdev->dev;
struct device_node *np = dev->of_node;
- unsigned int i;
int ret;

INIT_LIST_HEAD(&pcie->resources);
@@ -1179,15 +1178,34 @@ static int mvebu_pcie_parse_request_resources(struct mvebu_pcie *pcie)
resource_size(&pcie->io) - 1);
pcie->realio.name = "PCI I/O";

- for (i = 0; i < resource_size(&pcie->realio); i += SZ_64K)
- pci_ioremap_io(i, pcie->io.start + i);
-
pci_add_resource(&pcie->resources, &pcie->realio);
}

return devm_request_pci_bus_resources(dev, &pcie->resources);
}

+static void mvebu_pcie_map_io(struct mvebu_pcie *pcie)
+{
+ int i;
+
+ if (resource_size(&pcie->io) == 0)
+ return;
+
+ for (i = 0; i < resource_size(&pcie->realio); i += SZ_64K)
+ pci_ioremap_io(i, pcie->io.start + i);
+}
+
+static void mvebu_pcie_unmap_io(struct mvebu_pcie *pcie)
+{
+ int i;
+
+ if (resource_size(&pcie->io) == 0)
+ return;
+
+ for (i = 0; i < resource_size(&pcie->realio); i += SZ_64K)
+ pci_unmap_io(i);
+}
+
static int mvebu_pcie_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
@@ -1258,6 +1276,8 @@ static int mvebu_pcie_probe(struct platform_device *pdev)

pcie->nports = i;

+ mvebu_pcie_map_io(pcie);
+
list_splice_init(&pcie->resources, &bridge->windows);
bridge->dev.parent = dev;
bridge->sysdata = pcie;
@@ -1268,7 +1288,13 @@ static int mvebu_pcie_probe(struct platform_device *pdev)
bridge->align_resource = mvebu_pcie_align_resource;
bridge->msi = pcie->msi;

- return pci_host_probe(bridge);
+ ret = pci_host_probe(bridge);
+ if (ret) {
+ mvebu_pcie_unmap_io(pcie);
+ return ret;
+ }
+
+ return 0;
}

static const struct of_device_id mvebu_pcie_of_match_table[] = {

--
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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