Re: [PATCH V2 2/2] power: twl4030_charger: attempt to power off in case of critical events

From: Grazvydas Ignotas
Date: Wed Jun 04 2014 - 18:30:45 EST

On Wed, Jun 4, 2014 at 4:01 PM, Nishanth Menon <nm@xxxxxx> wrote:
> On 06/04/2014 05:04 AM, Grazvydas Ignotas wrote:
>> On Thu, May 29, 2014 at 12:46 AM, Nishanth Menon <nm@xxxxxx> wrote:
>>> Attempt to power off in case of critical events such as battery removal,
>>> over voltage events.
>>> There is no guarentee that we'd be in a safe scenario here, but the very
>>> least we can try to do is to power off the device to prevent damage to
>>> the system instead of just printing a message and hoping for the best.
>> At least "battery temperature out of range" does seem to happen quite
>> often while charging on hot summer day. I'd prefer my pandora to not
>> shutdown in such case, it could just stop charging instead.
> Yeah, We could call
> twl4030_charger_enable_ac(false);
> twl4030_charger_enable_usb(bci, false);
> But then, is that sufficient?
> From the TRM:
> 7.5.8 Battery Temperature Out-of-Range Detection
> Battery temperature out-of-range detection detects whether the battery
> temperature is within a specific
> range. Detection is possible for two temperature ranges. When the
> battery temperature is not in the
> 2â50ÂC range or is in the 3â43ÂC range, the TBATOR1 and TBATOR2 status
> bits rise and an interrupt is
> generated.
> This MADC monitoring function can be enabled by writing to the
> TBATOR2EN (BCIMFEN2[1]) fields.
> Battery pack at high temperature is a risk, no? and it may not be just
> charger that might be causing such a condition. Is'nt it safer to shut
> the device down in such a case?

I don't know, so far nobody has complained about the battery exploding
and anybody getting hurt, but it would make the device unusable for
people in hot climates. From what I remember the automatic charge is
stopped automatically on this condition, as some people complained
they couldn't charge their device and saw these messages in dmesg. I
guess mainline could choose the safer option and shutdown, no strong
opinion about this.

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