linux-kernel - Re: [PATCH v1] mfd: tps65910: Correct power-off programming sequence

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Date:   Fri, 15 May 2020 20:30:43 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Michał Mirosław <mirq-linux@...e.qmqm.pl>
Cc:     Tony Lindgren <tony@...mide.com>, Lee Jones <lee.jones@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Zack Pearsall <zpearsall@...oo.com>,
        linux-tegra@...r.kernel.org, linux-omap@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] mfd: tps65910: Correct power-off programming sequence

15.05.2020 16:30, Michał Mirosław пишет:
> On Thu, May 14, 2020 at 11:50:21PM +0300, Dmitry Osipenko wrote:
>> This patch fixes system shutdown on a devices that use TPS65910 as a
>> system's power controller. In accordance to the TPS65910 datasheet, the
>> PMIC's state-machine transitions into the OFF state only when DEV_OFF
>> bit of DEVCTRL_REG is set. The ON / SLEEP states also should be cleared,
>> otherwise PMIC won't get into a proper state on shutdown. Devices like
>> Nexus 7 tablet and Ouya game console are now shutting down properly.
>>
>> Tested-by: Zack Pearsall <zpearsall@...oo.com>
>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>> ---
>>  drivers/mfd/tps65910.c | 12 ++++++++++--
>>  1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mfd/tps65910.c b/drivers/mfd/tps65910.c
>> index 11959021b50a..22116cee411d 100644
>> --- a/drivers/mfd/tps65910.c
>> +++ b/drivers/mfd/tps65910.c
>> @@ -440,8 +440,16 @@ static void tps65910_power_off(void)
>>  			DEVCTRL_PWR_OFF_MASK) < 0)
>>  		return;
>>  
>> -	tps65910_reg_clear_bits(tps65910, TPS65910_DEVCTRL,
>> -			DEVCTRL_DEV_ON_MASK);
>> +	if (tps65910_reg_clear_bits(tps65910, TPS65910_DEVCTRL,
>> +			DEVCTRL_DEV_SLP_MASK) < 0)
>> +		return;
>> +
>> +	if (tps65910_reg_clear_bits(tps65910, TPS65910_DEVCTRL,
>> +			DEVCTRL_DEV_ON_MASK) < 0)
>> +		return;
>> +
>> +	tps65910_reg_set_bits(tps65910, TPS65910_DEVCTRL,
>> +			DEVCTRL_DEV_OFF_MASK);
>>  }
> 
> Isn't it enough to update the DEVCTRL with just one
> tps65910_reg_update_bits()?

IIRC, we've tried that variant and it didn't work. Although, maybe it
was affected by some other changes that we were trying simultaneously,
so could be worthwhile to re-check it. Thank you for the comment!