linux-kernel - Re: [PATCH v9 1/2] regulator: Add driver for max77802 PMIC PMIC regulators

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Date:	Mon, 25 Aug 2014 08:40:40 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Cc:	Yuvaraj Cd <yuvaraj.lkml@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Olof Johansson <olof@...om.net>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Abhilash Kesavan <a.kesavan@...sung.com>,
	Prashanth G <prashanth.g@...sung.com>,
	Alim Akhtar <alim.akhtar@...sung.com>,
	sunil joshi <joshi@...sung.com>
Subject: Re: [PATCH v9 1/2] regulator: Add driver for max77802 PMIC PMIC regulators

Javier,

On Mon, Aug 25, 2014 at 2:07 AM, Javier Martinez Canillas
<javier.martinez@...labora.co.uk> wrote:
> Hello Yuvaraj,
>
> On 08/25/2014 10:22 AM, Yuvaraj Cd wrote:
>>>> Good question. I'm not that familiar with the dw_mmc host controller nor
>>>> its driver implementation so I'll let Yuvaraj or Doug to answer that.
>> Well,here it goes!
>> 1. Power ON the board LDO4CTRL1[7:6] 11b
>> 2. dw_mmc driver enable the vqmmc.
>> 3. checks for UHS support, complete the voltage switching t0 1.8V
>> 4. Does warm reset by reboot command.
>> 5. mmc core calls mmc_set_ios() with MMC_POWER_OFF.
>> 6. dw_mmc driver cut-off the regulator with LDO4CTRL1[7:6] is 00b
>> 7.dw_mmc driver enable the vqmmc.
>>  But after step 7 also, LD4CTRL[7:6] is 00b.
>
> Ok, so the dw_mmc driver is enabling vqmmc, that's good.
>
>>>
>>> I haven't seen the issue that Yuvaraj is reporting (but I also haven't
>>> picked up all of the relevant patches and tried to reproduce), so I'm
>>> going to have to leave it to Yuvaraj to answer.
>>     static int max77802_enable(struct regulator_dev *rdev)
>>     {
>>       struct max77802_regulator_prv *max77802 = rdev_get_drvdata(rdev);
>>      int id = rdev_get_id(rdev);
>>      int shift = max77802_get_opmode_shift(id);
>>      return regmap_update_bits(rdev->regmap,
>> rdev->desc->enable_reg,rdev->desc->enable_mask,max77802->opmode[id] <<
>> shift);
>>   }
>> I think in the above code snippet, the "val" is what we got it during
>> the probe.We always write that value for enabling this regulator(which
>> is LDO4CTRL1[7:6] 00b after warm reset) which is not correct according
>> the MAX77802 manual.
>>>
>
> I see, so probably until we have a way to define the operating mode for
> each regulator using DT we should set the opmode to normal when enabling a
> regulator independently of the value the hardware register reported on probe.
>
> Can you please test the following change [0] so I can post as a proper
> patch? Doug, Mark do you think that forcing the regulator to opmode normal
> when enabling is the right solution here?

IMHO that makes sense.
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