how to fix acpi_pci_root_remap_iospace?

From: "Luck, Tony" <tony.luck@intel.com>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-kernel@vger.kernel.org,
	Jayachandran C <jchandra@broadcom.com>,
	Sinan Kaya <okaya@codeaurora.org>,
	Tomasz Nowicki <tn@semihalf.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Boris Brezillon <boris.brezillon@bootlin.com>,
	Miquel Raynal <miquel.raynal@bootlin.com>
Subject: how to fix acpi_pci_root_remap_iospace?
Date: Thu, 16 Aug 2018 13:45:07 -0700	[thread overview]
Message-ID: <20180816204506.GA21144@agluck-desk> (raw)

Bjorn,

Back in commit:

  0a70abb38062 ("PCI/ACPI: Support I/O resources when parsing host bridge resources")

we added acpi_pci_root_remap_iospace().  On ia64 this was a no-op because ia64
didn't define PCI_IOBASE, so the entire body of the function was skipped.

But in the current merge window commit:

  0bbf47eab469 ("ia64: use asm-generic/io.h")

ended up defining PCI_IOBASE for us, and now we die horribly
in early boot with:

  kernel BUG at lib/ioremap.c:72!


Is PCI_IOBASE the right thing to check for to decide whether
acpi_pci_root_remap_iospace() needs to do anything?

The ugly fix would be:

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 7433035ded95..de06377de13b 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -741,7 +741,7 @@ static void acpi_pci_root_validate_resources(struct device *dev,
 static void acpi_pci_root_remap_iospace(struct fwnode_handle *fwnode,
 			struct resource_entry *entry)
 {
-#ifdef PCI_IOBASE
+#if defined(PCI_IOBASE) && !defined(CONFIG_IA64)
 	struct resource *res = entry->res;
 	resource_size_t cpu_addr = res->start;
 	resource_size_t pci_addr = cpu_addr - entry->offset;

or we can do some other juggling with defines to get the
same outcome.

-Tony
