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

From: Doug Anderson
Date: Mon Aug 25 2014 - 11:40:59 EST


On Mon, Aug 25, 2014 at 2:07 AM, Javier Martinez Canillas
<javier.martinez@xxxxxxxxxxxxxxx> 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.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at