IO Daisychain feature has to be triggered whenever there is a change in
device's mux configuration (See section 3.9.4 in OMAP4 Public TRM vP).

Now devices can idle independent of the powerdomain, there can be a
window where device is idled and corresponding powerdomain can be
ON/INACTIVE state. In such situations, since both module wake up is
enabled at padlevel as well as io daisychain sequence is triggered,
there will be 2 PRCM interrupts (Module async wake up via swakeup and
IO Pad interrupt). But as PRCM Interrupt handler clears the Module
Padlevel WKST bit in the first interrupt, module specific interrupt
handler will not triggered for the second time

Also look at detailed explanation given by Rajendra at
http://www.spinics.net/lists/linux-serial/msg04480.htmlSigned-off-by: Vishwanath BS <vishwanath.bs@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Reviewed-by: Rajendra Nayak <rnayak@ti.com>
[paul@pwsan.com: remove dependency on pm.c & pm.h; add kerneldoc]
Signed-off-by: Paul Walmsley <paul@pwsan.com>