RE: [PATCH v2 1/2] mfd: dt: tps6586x: Add power off control

[Bill Huang]

nvpublic
> On 08/24/2012 06:36 PM, Bill Huang wrote:
> >>> On Sun, Aug 19, 2012 at 06:07:55PM -0700, Bill Huang wrote:
> >>>> Add DT property "ti,system-power-controller" telling whether or not
> >>>> this pmic is in charge of controlling the system power, so the
> >>>> power off routine can be hooked up to system call "pm_power_off".
> ...
> >>> I've seen the following while trying this patch applied on top of next-20120817:
> >>>
> >>> [   40.581151] Power down.
> >>> [   41.583160] ------------[ cut here ]------------
> >>> [   41.587784] WARNING: at /home/thierry.reding/src/kernel/linux-ipmp.git/drivers/i2c/busses/i2c-
> >>> tegra.c:525 tegra_i2c_xfer+0x21c/0x29c()
> ...
> >> Thanks Thierry, I can repro this on Tegra20 inconsistently and found,
> >> if current cpu is not cpu0 when doing "machine_shutdown" (it will
> >> call "smp_send_stop"), i2c controller will failed to do any transaction (looks like gic interrupt
> will be disabled), I'll debug further to find out the root cause.
> >>
> >> By the way, Tegra30 is good since it will always be cpu0 when doing
> >> "machine_shutdown", I still don't know why it makes the difference
> >> against Tegra20 since I'm not familiar with those cpu stuffs and what make it behave differently,
> I'll study a bit, thanks.
> >
> > I've sent the shutdown issue for discussion in ARM list: Shutdown problem in SMP system happened on
> Tegra20.
> > The cause of the i2c timeout is pretty clear now and it is not
> > directly related to this patch, so is this patch series acceptable? Any thoughts or comment? Thanks.
> 
> I tend to agree; power off never worked without this patch, and sometimes does with the patch, due to
> nothing wrong with this patch.
> 
> Bill, please do follow up on getting the underlying Tegra issue solved somehow though. IIRC, Joseph Lo
> or Prashant has a patch which enabled the config option that Russell mentioned, so the fix may just be
> to wait for that patch to get finalized, but please double-check that solves it.
> Thanks!

As per the shutdown issue discussion, enabling CONFIG_PM_SLEEP_SMP is the only solution and I've confirmed that fix the issue, thanks. 
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