Re: MFD USB host: prevents CORE retention in idle

[Kevin Hilman <khilman@ti.com>]

Kevin Hilman <khilman@ti.com> writes:

> "Munegowda, Keshava" <keshava_mgowda@ti.com> writes:
>
>> On Thu, May 24, 2012 at 5:55 AM, Kevin Hilman <khilman@ti.com> wrote:
>>> On 05/23/2012 05:01 PM, Kevin Hilman wrote:
>>>>
>>>> Hi Keshava,
>>>>
>>>> Using current l-o master, I noticed that CORE was not hitting retention
>>>> in idle on my 3530/Overo.  CORE hits retention on suspend just fine.
>>>>
>>>> Debugging this, I found that usbtll_fck was still enabled during idle,
>>>> thus preventing CORE from hitting retention.
>>>>
>>>> To test, I disabled USB host (CONFIG_MFD_OMAP_USB_HOST=n in .config) and
>>>> was then started seeing CORE hit retention in idle again.
>>>>
>>>> I have nothing plugged into the USB host port on this board, so I
>>>> would've expected that runtime PM would've kicked in and shutdown this
>>>> clock.
>>>>
>>>> Any ideas what's going on here?  Is this expected behavior?
>>>>
>>>
>>> If it helps, attached is a bootlog after enabling debug for
>>> mfd/omap-usb-host.c as well.  Notice there's a couple of clock-related
>>> warnings from this driver as well.  Not sure if they're relevant:
>>>
>>> usbhs_omap: alias fck already exists
>>> usbhs_omap usbhs_omap: xclk60mhsp2_ck set parentfailed error:-22
>>
>> these clocks were specific to omap4 and it should not cause any
>> problem to omap3 boards.
>
> OK, they seem unrelated to this CORE retention problem, but the warnings
> should still be understood and fixed.
>
>> I will try to reproduce this on 3430 sdp to explore further.
>
> Thanks for looking.  Note that I only saw this problem on my 3530
> platforms (Overo, OMAP3EVM.)  My 3430/n900 doesn't support USBHS host
> AFAICT, so didn't test there.

After realizing that the same IP should exist on 3430/n900, I copied
some board file support for USBHS host from overo into the n900 board
file in order to test on 3430/n900.  

Problem exists on n900 too.

Kevin
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