When trying to build 2.6.27-git8 on x86 with CONFIG_MFD_WM8350_I2C=m,
make aborts with:

  CHECK   drivers/mfd/wm8350-core.c
drivers/mfd/wm8350-core.c:1220:13: error: undefined identifier 'NO_IRQ'
  CC [M]  drivers/mfd/wm8350-core.o
drivers/mfd/wm8350-core.c: In function 'wm8350_device_init':
drivers/mfd/wm8350-core.c:1220: error: 'NO_IRQ' undeclared (first use in this function)
drivers/mfd/wm8350-core.c:1220: error: (Each undeclared identifier is reported only once
drivers/mfd/wm8350-core.c:1220: error: for each function it appears in.)
make[2]: *** [drivers/mfd/wm8350-core.o] Error 1

After deselecting CONFIG_MFD_WM8350_I2C, make completes fine.

HTH
T.