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

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Message-ID: <CAD=FV=WC0h7fYm2QFqu3Zka7CsU4BtG-oyPpJav+ygC+gmCR+A@mail.gmail.com>
Date:	Fri, 22 Aug 2014 15:15:04 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Cc:	Mark Brown <broonie@...nel.org>,
	Yuvaraj Cd <yuvaraj.lkml@...il.com>,
	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

Hi,

On Fri, Aug 22, 2014 at 3:02 PM, Javier Martinez Canillas
<javier.martinez@...labora.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.

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.

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
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