From: Yuvaraj Cd <yuvaraj.lkml@gmail.com>
To: Doug Anderson <dianders@chromium.org>
Cc: Javier Martinez Canillas <javier.martinez@collabora.co.uk>,
Mark Brown <broonie@kernel.org>, Olof Johansson <olof@lixom.net>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Abhilash Kesavan <a.kesavan@samsung.com>,
Prashanth G <prashanth.g@samsung.com>,
Alim Akhtar <alim.akhtar@samsung.com>,
sunil joshi <joshi@samsung.com>
Subject: Re: [PATCH v9 1/2] regulator: Add driver for max77802 PMIC PMIC regulators
Date: Mon, 25 Aug 2014 13:52:04 +0530 [thread overview]
Message-ID: <CA+NduCCT-KQ=gh7QWkBE4qkA2YOJ8KCVqbkC6Tkmb1aPvCsGFQ@mail.gmail.com> (raw)
In-Reply-To: <CAD=FV=WC0h7fYm2QFqu3Zka7CsU4BtG-oyPpJav+ygC+gmCR+A@mail.gmail.com>
On Sat, Aug 23, 2014 at 3:45 AM, Doug Anderson <dianders@chromium.org> wrote:
> Hi,
>
> On Fri, Aug 22, 2014 at 3:02 PM, Javier Martinez Canillas
> <javier.martinez@collabora.co.uk> wrote:
>> Hello Mark,
>>
>> On 08/22/2014 08:30 PM, Mark Brown wrote:
>>>
>>>> The problem is that one of these regulators is used as the vqmmc-supply
>>>> (VCCQ/VDD_IO) so the mmc host controller driver disables it on
>>>> MMC_POWER_OFF. Now AFAIK (Yuvaraj can correct me what I got wrong) this
>>>> shouldn't be an issue since on card detection, the vqmmc supply should be
>>>> enabled again but on Exynos the built-in card detect line is on the same
>>>> power rail as vqmmc. That means that disabling the regulator prevents card
>>>> insertions to be detected.
>>>
>>> If the MMC host controller needs a supply enabling in order to do card
>>> detection and it's supposed to be doing card detection I'd expect it to
>>> be enabling that supply. Why is it not doing that?
>>>
>>
>> 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.
>
> 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.
>
> As far as I know the dw_mmc driver ought to be enabling vqmmc when it
> needs it. Perhaps there's a bug in your patch series that adds vqmmc
> support to dw_mmc?
>
> -Doug
next prev parent reply other threads:[~2014-08-25 8:22 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-18 8:32 [PATCH v9 0/2] Add Maxim 77802 regulator support Javier Martinez Canillas
2014-08-18 8:32 ` [PATCH v9 1/2] regulator: Add driver for max77802 PMIC PMIC regulators Javier Martinez Canillas
2014-08-18 15:23 ` Mark Brown
2014-08-22 6:01 ` Yuvaraj Cd
2014-08-22 12:15 ` Javier Martinez Canillas
2014-08-22 14:45 ` Mark Brown
2014-08-22 17:53 ` Javier Martinez Canillas
2014-08-22 18:30 ` Mark Brown
2014-08-22 22:02 ` Javier Martinez Canillas
2014-08-22 22:15 ` Doug Anderson
2014-08-25 8:22 ` Yuvaraj Cd [this message]
2014-08-25 9:07 ` Javier Martinez Canillas
2014-08-25 10:46 ` Yuvaraj Cd
2014-08-25 15:40 ` Doug Anderson
2014-08-25 17:20 ` Javier Martinez Canillas
2014-08-26 7:17 ` Mark Brown
2014-08-26 9:08 ` Javier Martinez Canillas
2014-08-26 9:12 ` Mark Brown
2014-08-18 8:32 ` [PATCH v9 2/2] regulator: Add DT bindings for max77802 " Javier Martinez Canillas
2014-08-18 15:23 ` Mark Brown
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