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Message-ID: <6f6dfaa2-f529-c9fe-7dde-402c92f0daf6@quicinc.com>
Date: Mon, 19 Feb 2024 11:06:39 +0800
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Subject: Re: [PATCH] regulator: qcom-rpmh: Fix pm8010 pmic5_pldo502ln minimum
 voltage
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To: Bryan O'Donoghue <bryan.odonoghue@linaro.org>,
        Mark Brown
	<broonie@kernel.org>
CC: <andersson@kernel.org>, <konrad.dybcio@linaro.org>, <lgirdwood@gmail.com>,
        <quic_collinsd@quicinc.com>, <linux-arm-msm@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
References: <20240214121614.2723085-1-bryan.odonoghue@linaro.org>
 <13baed68-1014-4a48-874a-94027a6dd061@sirena.org.uk>
 <f38468b4-8b16-4180-9738-0a2b557651a1@linaro.org>
 <dcce3fa9-ecf3-42be-adf6-ca653a79ba2e@sirena.org.uk>
 <3851e21f-f8cb-487b-9ed4-9975949ff922@linaro.org>
 <a09d6450-95e7-4ed6-a0ad-5e7bb661533a@sirena.org.uk>
 <df6a49f3-88e9-46b4-b7c3-e5419fd01eca@linaro.org>
From: Fenglin Wu <quic_fenglinw@quicinc.com>
In-Reply-To: <df6a49f3-88e9-46b4-b7c3-e5419fd01eca@linaro.org>
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On 2024/2/15 6:47, Bryan O'Donoghue wrote:
> On 14/02/2024 14:52, Mark Brown wrote:
>> On Wed, Feb 14, 2024 at 02:44:56PM +0000, Bryan O'Donoghue wrote:
>>> On 14/02/2024 14:13, Mark Brown wrote:
>>
>>>> Not just that but also note that every voltage step in the range will
>>>> have the 8mV offset added.
>>
>>> The documents I have just show sensors attached to ldo3, ldo4 and 
>>> ldo6 fixed
>>> at 1.808.
>>
>>> I don't think there's any better or different information than a 
>>> +200000uV
>>> increment TBH.
>>
>> This seems like a very surprising and unusual hardware design, the
>> 1.808V voltage is already unusual.  Note that this may break systems
>> that are trying to set a range of say 1.8-2.0V if they actually need to
>> set 2V.
> 
> Hmm. I'm sure the rail value should be 1.808 its all over the 
> documentation for example when we get to index 3 we hit 2608000
> 
> REGULATOR_LINEAR_RANGE(1808000, 0,  2,  200000),
> 1808000 0
> 2008000 1
> 2208000 2
> 2408000 x
> REGULATOR_LINEAR_RANGE(2608000, 3,  28, 16000),
> 
> And there are other rails @ 1v8 if 1v8
> 
> The one thing I can't easily verify is index 0 = 1808000 and not say 
> 1800000 or indeed that the increment is 200000 and not say 8000.
> 
> I'll see if I can ask around with the hw people and get a more complete 
> answer.
> 
> Similarly now that you've gotten me digging into this problem, it's not 
> clear to me why this regulator isn't just a linear regulator with an 8mv 
> increment over a range of indexes.
> 
> At least the documentation I'm looking at doesn't elucidate.
> 
> I'll dig some more.
Please see the voltage steps for LDO3/4/6 described in the PM8010 TDOS 
document which is the most authoritative that we used internally for 
PMIC driver development:

Index	Vset (mV)
0	1800
1	2000
2	2200
3	2608
4	2624
5	2640
6	2656
7	2672
8	2688
9	2704
10	2720
11	2736
12	2752
13	2768
14	2784
15	2800
16	2816
17	2832
18	2848
19	2864
20	2880
21	2896
22	2912
23	2928
24	2944
25	2960
26	2976
27	2992
28	3008
29	3104
30	3200
31	3312

And I do see from the document change history that step 0 was changed 
from 1808mV and step 2 was changed from 2512mV, I don't know the reason 
of the change though.

Fenglin

> 
> ---
> bod
>