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    SubjectRe: [PATCH 4/4] mfd: global Suspend and resume support of ehci and ohci
    On Thu, Jun 2, 2011 at 5:36 AM, Kevin Hilman <> wrote:
    > Keshava Munegowda <> writes:
    >> From: Keshava Munegowda <>
    >> The global suspend and resume functions for usbhs core driver
    >> are implemented.These routine are called when the global suspend
    >> and resume occurs. Before calling these functions, the
    >> bus suspend and resume of ehci and ohci drivers are called
    >> from runtime pm.
    >> Signed-off-by: Keshava Munegowda <>
    > First, from what I can see, this is only a partial implementation of
    > runtime PM.  What I mean is that the runtime PM methods are used only
    > during the suspend path.  The rest of the time the USB host IP block is
    > left enabled, even when nothing is connected.
    > I tested this on my 3530/Overo board, and verified that indeed the
    > usbhost powerdomain hits retention on suspend, but while idle, when
    > nothing is connected, I would expect the driver could be clever enough
    > to use runtime PM (probably using autosuspend timeouts) to disable the
    > hardware as well.
    >> ---
    >>  drivers/mfd/omap-usb-host.c |  103 +++++++++++++++++++++++++++++++++++++++++++
    >>  1 files changed, 103 insertions(+), 0 deletions(-)
    >> diff --git a/drivers/mfd/omap-usb-host.c b/drivers/mfd/omap-usb-host.c
    >> index 43de12a..32d19e2 100644
    >> --- a/drivers/mfd/omap-usb-host.c
    >> +++ b/drivers/mfd/omap-usb-host.c
    >> @@ -146,6 +146,10 @@
    >>  #define is_ehci_hsic_mode(x) (x == OMAP_EHCI_PORT_MODE_HSIC)
    >> +/* USBHS state bits */
    >> +#define OMAP_USBHS_INIT              0
    >> +#define OMAP_USBHS_SUSPEND   4
    > These additional state bits don't seem to be necessary.
    > For suspend, just check 'pm_runtime_is_suspended()'
    > The init flag is only used in the suspend/resume hooks, but the need for
    > it is a side effect of not correctly using the runtime PM callbacks.
    > Remember that the runtime PM get/put hooks have usage counting.  Only
    > when the usage count transitions to/from zero is the actual
    > hardware-level enable/disable (via omap_hwmod) being done.
    > The current code is making the assumption that every call to get/put is
    > going to result in an enable/disable of the hardware.
    > Instead, all of the code that needs to be run only upon actual
    > enable/disable of the hardware should be done in the driver's
    > runtime_suspend/runtime_resume callbacks.  These are only called when
    > the hardware actually changes state.
    > Not knowing that much about the EHCI block, upon first glance, it looks
    > like mmuch of what is done in usbhs_enable() should actually be done in
    > the ->runtime_resume() callback, and similarily, much of what is done in
    > usbhs_disable() should be done in the ->runtime_suspend() callback.

    do you mean driver->runtime_resume and driver->runtime_resume call backs.
    are these call backs from pm_runtime_get_sync and pm_runtime_put_sync?
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