Dear All,
We are working on omap4470 based device,kernel-3.0.31 is running on this.
In our device modem is connected to OMAP4470 using USB EHCI.
In our current kernel code, clocks are enabled when ports get connected
and disabled during disconnect.Due to this current consumption is more in
idle use case.
I have tried to put the host in smart idle/standby mode,due to erratas around
Host doesn't allow us
use smart idle/standby capabilities.
1) i571: USB host EHCI may stall when entering smart-standby mode
2) i660: USBHOST Configured In Smart-Idle Can Lead To a Deadlock
we are thinking to implement USB EHCI runtime suspend/resume feature.
In kernel-3.0.31 architecture the usbcore driver is parent of ehci and ohci
drivers.
The ehci and ohci drivers call the pm_runtime_get_sync and
pm_runtime_put_sync of parent device usbhs core.
From the ehci-omap driver what i can see only partial implementation of
runtime PM.
what i mean is that runtime PM methods are used only during the normal
suspend path
and when nothing is connected to ports(modem disconnected in our case).
I am thinking to change the ehci driver code, could claver enough to use
runtime PM
to disable the hardware when modem is connected and the system is in idle
state.
Kindly guide me how can i go about this.
Let me know if you need further clarification from me on this.
Thanks for spending your valuable time .......:)
Cheers
Bharath
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