Re: [PATCH V3] usb: musb: Fix unstable init of OTG_INTERFSEL.

[Grazvydas Ignotas <notasas-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Wed, Dec 18, 2013 at 5:35 PM, Felipe Balbi <balbi-l0cyMroinI0@public.gmane.org> wrote:
> Hi,
>
> On Tue, Dec 17, 2013 at 05:48:33PM +0100, anaumann-ZKHRqZ6+gQUX0D0ZMPkEVw@public.gmane.org wrote:
>> From: Andreas Naumann <anaumann-ZKHRqZ6+gQUX0D0ZMPkEVw@public.gmane.org>
>>
>> This is a hard to reproduce problem which leads to non-functional
>> USB-OTG port in 0.1%-1% of all boots. Tracked it down to commit
>> e25bec160158abe86c276d7d206264afc3646281, which introduces save/restore
>> of OTG_INTERFSEL over suspend.
>> Since the resume function is also called early in driver init, it uses a
>> non-initialized value (which is 0 and a non-supported setting in DM37xx
>> for INTERFSEL). Shortly after the correct value is set. Apparently this
>> works most time, but not always.
>
> yeah, but the problem is not on the glue layer. The bug is omap_device
> and pm_runtime not agreeing on device's state. I suppose there was a fix
> for that recently in linux-omap@vger mailing list.

You mean this: http://marc.info/?t=138444882600003&r=1&w=2 ?

This looks like a different issue during suspend, this problem is at
startup. Both musb_core and omap2430.c expect hardware to be disabled
on startup, and that works as expected. The problem is on first
pm_runtime_get_sync(), which results in first runtime_resume() call,
musb_core checks for first resume and doesn't load yet-unset context
in that case, however glue does and breaks things. We have this
problem since 3.2.


Gražvydas
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