On Thu, 29 Sep 2011 13:35:16 -0700
Randy Dunlap [off-list ref] wrote:

From: Randy Dunlap <redacted>

Fix build when CONFIG_X86_INTEL_MID is enabled but
CONFIG_X86_MRST is not enabled.  Fixes this build error:

This looks wrong. Unfortunately until we get kernel.org back its hard to
do much about it and see what is in all the trees.

-#ifdef CONFIG_X86_INTEL_MID
+#ifdef CONFIG_X86_MRST
 
 static inline enum mrst_cpu_type mrst_identify_cpu(void)
 {
 	return __mrst_cpu_chip;
 }
 
-#else /* !CONFIG_X86_INTEL_MID */
+#else /* !CONFIG_X86_MRST */
 
 #define mrst_identify_cpu()    (0)
 
-#endif /* !CONFIG_X86_INTEL_MID */
+#endif /* !CONFIG_X86_MRST */

This breaks Medfield so NAK

The correct behaviour should be 

INTEL_MID defined -> mrst_cpu_chip has meaning
INTEL_MID not defined -> mrst_identify_chip is 0

your change makes it 0 for Medfield which means it will crash on boot.