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

From: Bill Huang <bilhuang@nvidia.com>
To: "'Stephen Warren'" <swarren@wwwdotorg.org>
Cc: "'Thierry Reding'" <thierry.reding@avionic-design.de>,
	"'sameo@linux.intel.com'" <sameo@linux.intel.com>,
	"'grant.likely@secretlab.ca'" <grant.likely@secretlab.ca>,
	"'rob.herring@calxeda.com'" <rob.herring@calxeda.com>,
	"'rob@landley.net'" <rob@landley.net>,
	"'broonie@opensource.wolfsonmicro.com'" 
	<broonie@opensource.wolfsonmicro.com>,
	Laxman Dewangan <ldewangan@nvidia.com>, Xin Xie <xxie@nvidia.com>,
	"'lrg@slimlogic.co.uk'" <lrg@slimlogic.co.uk>,
	"'jhovold@gmail.com'" <jhovold@gmail.com>,
	"'kyle.manna@fuel7.com'" <kyle.manna@fuel7.com>,
	Rhyland Klein <rklein@nvidia.com>,
	"'devicetree-discuss@lists.ozlabs.org'" 
	<devicetree-discuss@lists.ozlabs.org>,
	"'linux-doc@vger.kernel.org'" <linux-doc@vger.kernel.org>,
	"'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v2 1/2] mfd: dt: tps6586x: Add power off control
Date: Mon, 27 Aug 2012 13:40:51 +0800	[thread overview]
Message-ID: <A7051F87A141B744BCAF487D48E5B3BDF5BA98284E@HKMAIL02.nvidia.com> (raw)
In-Reply-To: <503847C2.3080400@wwwdotorg.org>

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. 