hi，
after read about pci iomap code, I found some inconsistence in
function pci_iomap() for x86 platform.
I don't know whether it's indeed an inconsistence or an intended
design, or somewhere I'm wrong?
see:
pci_iomap(), for x86 platform, is defined in
include/asm-generic/iomap.h and it has a implementation in
lib/iomap.c, that is,
void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
{
resource_size_t start = pci_resource_start(dev, bar);
resource_size_t len = pci_resource_len(dev, bar);
unsigned long flags = pci_resource_flags(dev, bar);
if (!len || !start)
return NULL;
if (maxlen && len > maxlen)
len = maxlen;
if (flags & IORESOURCE_IO)
return ioport_map(start, len);
if (flags & IORESOURCE_MEM) {
if (flags & IORESOURCE_CACHEABLE)
return ioremap(start, len);
return ioremap_nocache(start, len);
}
/* What? */
return NULL;
}
from which, we can see,
if (flags & IORESOURCE_CACHEABLE)
return ioremap(start, len);
but, after look into ioremap, i found its x86 implementation(in
arch/x86/include/asm/io.h) is
static inline void __iomem *ioremap(resource_size_t offset, unsigned long size)
{
return ioremap_nocache(offset, size);
}
so, ioremap is not the cached version as expected.
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