On Wed, 13 May 2015, Toshi Kani wrote:
__ioremap_caller() calls reserve_memtype() to set new_pcm
(existing map type if any), and then calls
is_new_memtype_allowed() to verify if converting to new_pcm
is allowed when pcm (request type) is different from new_pcm.
When WT is requested, the caller expects that writes are
ordered and uncached. Therefore, this patch changes
is_new_memtype_allowed() to disallow the following cases.
- If the request is WT, mapping type cannot be WB
- If the request is WT, mapping type cannot be WC
Signed-off-by: Toshi Kani <toshi.kani(a)hp.com>
Reviewed-by: Thomas Gleixner <tglx(a)linutronix.de>