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

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Message-ID: <53FAFCBC.2050407@collabora.co.uk>
Date:	Mon, 25 Aug 2014 11:07:08 +0200
From:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
To:	Yuvaraj Cd <yuvaraj.lkml@...il.com>,
	Doug Anderson <dianders@...omium.org>
CC:	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

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?

Best regards,
Javier

[0]
diff --git a/drivers/regulator/max77802.c b/drivers/regulator/max77802.c
index ad1caa9..917b5ab 100644
--- a/drivers/regulator/max77802.c
+++ b/drivers/regulator/max77802.c
@@ -180,7 +180,7 @@ static int max77802_enable(struct regulator_dev *rdev)

        return regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
                                  rdev->desc->enable_mask,
-                                 max77802->opmode[id] << shift);
+                                 MAX77802_OPMODE_NORMAL << shift);
 }
--
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