Re: [PATCH] arm: dts: fix rk3066a based boards vdd_log voltage initialization

Andy Yan
2016-09-19T09:59:32Z

Hi Boris:

On 2016年09月19日 17:44, Boris Brezillon wrote:
> On Mon, 19 Sep 2016 17:38:10 +0800
> Andy Yan <andy.yan@rock-chips.com> wrote:
>
>> On 2016年09月19日 17:25, Boris Brezillon wrote:
>>> On Mon, 19 Sep 2016 16:44:56 +0800
>>> Andy Yan <andy.yan@rock-chips.com> wrote:
>>>
>>>> The current rk3066a based boards(Rayeager, Bqcurie2, Marsboard) use
>>>> pwm modulate vdd_logic voltage, but the pwm is default disabled and
>>>> the pwm pin acts as a gpio before pwm regulator probed, so the pwm
>>>> regulator driver will get a zero dutycycle at probe time, so change
>>>> the initial dutycycle to zero to match pwm_regulator_init_state check.
>>>>
>>>> Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
>>>>
>>>> ---
>>>>
>>>> arch/arm/boot/dts/rk3066a-bqcurie2.dts | 2 +-
>>>> arch/arm/boot/dts/rk3066a-marsboard.dts | 2 +-
>>>> arch/arm/boot/dts/rk3066a-rayeager.dts | 2 +-
>>>> 3 files changed, 3 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/arch/arm/boot/dts/rk3066a-bqcurie2.dts b/arch/arm/boot/dts/rk3066a-bqcurie2.dts
>>>> index bc674ee..618450d 100644
>>>> --- a/arch/arm/boot/dts/rk3066a-bqcurie2.dts
>>>> +++ b/arch/arm/boot/dts/rk3066a-bqcurie2.dts
>>>> @@ -61,7 +61,7 @@
>>>> regulator-min-microvolt = <1200000>;
>>>> regulator-max-microvolt = <1200000>;
>>>> regulator-always-on;
>>>> - voltage-table = <1000000 100>,
>>>> + voltage-table = <1000000 0>,
>>>> <1200000 42>;
>>> So, it seems you are reversing the PWM polarity here. Are you sure you
>>> shouldn't change the 2nd entry of this table (<1200000 58>)?
>>
>> no, 42% duty cycle give a stable 1.2v vdd_logic voltage on my
>> board. As i explained in the commit, the pwm was default at a disabled
>> state before regulator_register success at pwm_regulator probe, so
>> pwm_regulator_init_state function will get a zero dutycycle from
>> pwm_get_relative_dutycycle. I have to change the dutycycle of fist
>> table to zero to match the following check, other wise the function will
>> return defualt value(-EINVAL), then the pwm regulator register failed.
> Is 0% duty really producing a 1V output, or are you just changing it to
> make it work?

no, I'm not sure 0% duty is really producing a 1v output, maybe the
100% duty producing a 1v output, I just changing it to make it work on
your Patch. Before the pwm regulator registered success, the pwm output
pin act as a stable gpio at a hight or low level(depends on the soc
power on state) to control a 1v output.
>
> BTW, I'm not sure we should fail when the current PWM state does not
> match one of the value in the voltage-table.

Yes, the previous version don't have the state check, so the
regulator can register success.
>
>>>
>>>> status = "okay";
>>>> };
>>>> diff --git a/arch/arm/boot/dts/rk3066a-marsboard.dts b/arch/arm/boot/dts/rk3066a-marsboard.dts
>>>> index a2b763e..ddc680b 100644
>>>> --- a/arch/arm/boot/dts/rk3066a-marsboard.dts
>>>> +++ b/arch/arm/boot/dts/rk3066a-marsboard.dts
>>>> @@ -59,7 +59,7 @@
>>>> regulator-min-microvolt = <1200000>;
>>>> regulator-max-microvolt = <1200000>;
>>>> regulator-always-on;
>>>> - voltage-table = <1000000 100>,
>>>> + voltage-table = <1000000 0>,
>>>> <1200000 42>;
>>>> status = "okay";
>>>> };
>>>> diff --git a/arch/arm/boot/dts/rk3066a-rayeager.dts b/arch/arm/boot/dts/rk3066a-rayeager.dts
>>>> index 2536b3a..30aee99 100644
>>>> --- a/arch/arm/boot/dts/rk3066a-rayeager.dts
>>>> +++ b/arch/arm/boot/dts/rk3066a-rayeager.dts
>>>> @@ -84,7 +84,7 @@
>>>> regulator-min-microvolt = <1200000>;
>>>> regulator-max-microvolt = <1200000>;
>>>> regulator-always-on;
>>>> - voltage-table = <1000000 100>,
>>>> + voltage-table = <1000000 0>,
>>>> <1200000 42>;
>>>> status = "okay";
>>>> };
>>>
>>>
>>
>
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