serial: sh-sci: console runtime PM support (revisit)
authorTeppei Kamijou <teppei.kamijou.yb@renesas.com>
Fri, 16 Nov 2012 01:51:55 +0000 (10:51 +0900)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 16 Nov 2012 02:02:36 +0000 (18:02 -0800)
commit0174e5ca82ba6bd62ab870e5781b72bd5397f1c3
tree1a57c3e61950d111952a20fcedd966d9713ed471
parent00cadbfd1e73fb9951da7d2358c39b561c017ea3
serial: sh-sci: console runtime PM support (revisit)

The commit 1ba7622094 (serial: sh-sci: console Runtime PM support,
from Magnus Damm <damm@opensource.se>, 2011-08-03), tried to support
console runtime PM, but unfortunately it didn't work for us for some
reason.  We did not investigated further at that time, instead would
like to propose a different approach.

In Linux tty/serial world, to get console PM work properly, a serial
client driver does not have to maintain .runtime_suspend()/..resume()
calls itself, but can leave console power power management handling to
the serial core driver.

This patch moves the sh-sci driver in that direction.

Notes:

* There is room to optimize console runtime PM more aggressively by
  maintaining additional local runtime PM calls, but as a first step
  having .pm() operation would suffice.

* We still have a couple of direct calls to sci_port_enable/..disable
  left in the driver.  We have to live with them, because they're out
  of serial core's help.

Signed-off-by: Teppei Kamijou <teppei.kamijou.yb@renesas.com>
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/serial/sh-sci.c