[PATCH 4/4] lib/iomap.c: improve comment about pci anomaly

[Philipp Stanner <pstanner@redhat.com>]

lib/iomap.c contains one of the definitions of pci_iounmap(). The
current comment above this out-of-place function does not clarify WHY
the function is defined here.

Linus's detailed comment above pci_iounmap() in drivers/pci/iomap.c
clarifies that in a far better way.

Extend the existing comment with an excerpt from Linus's and hint at the
other implementation in drivers/pci/iomap.c

Signed-off-by: Philipp Stanner <pstanner@redhat.com>
---
 lib/iomap.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/lib/iomap.c b/lib/iomap.c
index 4f8b31baa575..647aac8ea3e3 100644
--- a/lib/iomap.c
+++ b/lib/iomap.c
@@ -419,8 +419,17 @@ EXPORT_SYMBOL(ioport_unmap);
 #endif /* CONFIG_HAS_IOPORT_MAP */
 
 #ifdef CONFIG_PCI
-/* Hide the details if this is a MMIO or PIO address space and just do what
- * you expect in the correct way. */
+/*
+ * Hide the details if this is a MMIO or PIO address space and just do what
+ * you expect in the correct way.
+ *
+ * pci_iounmap() somewhat illogically comes from lib/iomap.c for the
+ * CONFIG_GENERIC_IOMAP case, because that's the code that knows about
+ * the different IOMAP ranges.
+ *
+ * For more details see also the pci_iounmap() implementation in
+ * drivers/pci/iomap.c
+ */
 void pci_iounmap(struct pci_dev *dev, void __iomem * addr)
 {
 	IO_COND(addr, /* nothing */, iounmap(addr));
-- 
2.41.0