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Date: Wed, 29 Jun 2011 20:52:30 +0530 From: "Munegowda, Keshava" <keshava_mgowda@...com> To: Kevin Hilman <khilman@...com> Cc: linux-usb@...r.kernel.org, linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org, balbi@...com, gadiyar@...com, sameo@...ux.intel.com, parthab@...ia.ti.com, tony@...mide.com, b-cousson@...com, paul@...an.com Subject: Re: [PATCH 4/4] mfd: global Suspend and resume support of ehci and ohci On Thu, Jun 2, 2011 at 5:36 AM, Kevin Hilman <khilman@...com> wrote: > Keshava Munegowda <keshava_mgowda@...com> writes: > >> From: Keshava Munegowda <Keshava_mgowda@...com> >> >> 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 <keshava_mgowda@...com> > > 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. Kevin, 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? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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