On 13/09/2021 20:32, Sebastian Krzyszkowiak wrote:
> On poniedziałek, 13 września 2021 15:02:34 CEST Krzysztof Kozlowski wrote:
>> On 12/09/2021 22:54, Sebastian Krzyszkowiak wrote:
>>> The gauge requires us to clear the status bits manually for some alerts
>>> to be properly dismissed. Previously the IRQ was configured to react only
>>> on falling edge, which wasn't technically correct (the ALRT line is active
>>> low), but it had a happy side-effect of preventing interrupt storms
>>> on uncleared alerts from happening.
>>>
>>> Fixes: 7fbf6b731bca ("power: supply: max17042: Do not enforce (incorrect)
>>> interrupt trigger type") Cc: <stable@xxxxxxxxxxxxxxx>
>>> Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@xxxxxxx>
>>> ---
>>>
>>> drivers/power/supply/max17042_battery.c | 3 +++
>>> 1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/power/supply/max17042_battery.c
>>> b/drivers/power/supply/max17042_battery.c index
>>> 8dffae76b6a3..c53980c8432a 100644
>>> --- a/drivers/power/supply/max17042_battery.c
>>> +++ b/drivers/power/supply/max17042_battery.c
>>> @@ -876,6 +876,9 @@ static irqreturn_t max17042_thread_handler(int id,
>>> void *dev)>
>>> max17042_set_soc_threshold(chip, 1);
>>>
>>> }
>>>
>>> + regmap_clear_bits(chip->regmap, MAX17042_STATUS,
>>> + 0xFFFF & ~(STATUS_POR_BIT |
> STATUS_BST_BIT));
>>> +
>>
>> Are you sure that this was the reason of interrupt storm? Not incorrect
>> SoC value (read from register for ModelGauge m3 while not configuring
>> fuel gauge model).
>
> Yes, I am sure. I have observed this on a fully configured max17055 with
> ModelGauge m5. It also makes sense to me based on what I read in the code and
> datasheets.
>
> There were two kinds of storms - the short ones happening on each SOC change
> caused by SOC threshold alerts set by max17042_set_soc_threshold which
> eventually got cleared by reconfiguring the thresholds; and a huge one
> happening when SOC got down to 0% that did not get away until the battery got
> charged to at least 1% at which point the thresholds got reconfigured again
> (which is how I noticed the underflow fixed by the second patch).
OK, undestood.
>
> Besides, I also have patches for configuring m5 gauge via DT that I'll send
> once I clean them up.
That's cool! Happy to see such work.
>
>> You should only clear bits which you are awaken for... Have in mind that
>> in DT-configuration the fuel gauge is most likely broken by missing
>> configuration. With alert enabled, several other config fields should be
>> cleared.
>
> I have checked all the bits in the Status register and aside of Bst, POR and
> bunch of "don't-care" bits they're all alert indicators that we either handle
> explicitly in the interrupt handler (Smn/Smx) or implicitly via
> power_supply_changed (Imn/Imx, Vmn/Vmx, Tmn/Tmx, dSOCi, Bi/Br). The driver
> unconditionally enables alerts for SOC thresholds and all the rest stays
> effectively disabled at POR; however, a bootloader or firmware may configure it
> differently, which may be wanted for things like resuming from suspend when a
> bad condition happens. Therefore we need to clear all the bits anyway and I'm
> not sure whether iterating through them in a "if set then clear" loop gains us
> anything aside of additional lines of code.
Seems reasonable, you're right. Could you mention this expolanation in
commit msg or comment in the code?
Best regards,
Krzysztof
