From: Doug Anderson <dianders@chromium.org>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: "addy ke" <addy.ke@rock-chips.com>,
"Rob Herring" <robh+dt@kernel.org>,
"Pawel Moll" <pawel.moll@arm.com>,
"Mark Rutland" <mark.rutland@arm.com>,
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"Randy Dunlap" <rdunlap@infradead.org>,
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"Chris Ball" <chris@printf.net>,
"Dinh Nguyen" <dinguyen@altera.com>,
"Heiko Stübner" <heiko@sntech.de>,
"Olof Johansson" <olof@lixom.net>,
"Sonny Rao" <sonnyrao@chromium.org>,
"Alexandru Stan" <amstan@chromium.org>,
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Subject: Re: [PATCH] mmc: dw_mmc: try pick the exact same voltage as vmmc for vqmmc
Date: Mon, 24 Nov 2014 21:29:28 -0800 [thread overview]
Message-ID: <CAD=FV=UZT91rp2rgPCh5mY5s+g8J3iOrDsHKjuXAgEqoye5goQ@mail.gmail.com> (raw)
In-Reply-To: <CAPDyKFqt4rrwi940KAPyPONpjixK1730QmHEsN27V97jyHH+Qw@mail.gmail.com>
Ulf,
On Mon, Nov 24, 2014 at 5:29 AM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>> 2. Several people I've talked to have expressed concerns that our
>> minimum value is 2.7V. Apparently that's really on the edge and makes
>> EEs a little nervous. The quick sample of cards sitting on my desk
>> shows that they seem to claim 0x00ff8000, which doesn't include 2.7V.
>
> 0x00ff8000 states what values of VDD levels the device supports. Not VIO.
Yup, I was just pointing out that possibly others were trying to get a
little bit of margin (not going all the way down to 2.7V) too.
>> Both of the above make me feel like dw_mmc should try its best to pick
>> a value for vqmmc that is closest to the value of vmmc (and >= 2.7V).
>> That also happens to make us work exactly like hosts where vmmc and
>> vqmmc are supplied by the same supply.
>
> I do see your point. And I agree that it would be nice to achieve
> something like this.
>
> The question is how to do this. For sure, we need to involve the mmc
> core to handle this correctly.
You could add a function to the core that we could call from
dw_mci_switch_voltage() and it would do all the work except trying to
set the UHS register. That would certainly make it easy. That could
try to set the highest voltage that is <= vmmc when we're at
MMC_SIGNAL_VOLTAGE_330.
-Doug
next prev parent reply other threads:[~2014-11-25 5:29 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-30 2:21 [PATCH] mmc: dw_mmc: add a quirk for the defferent bit of sdio interrupt Addy Ke
2014-10-30 4:35 ` Jaehoon Chung
2014-10-30 4:41 ` Doug Anderson
2014-10-30 4:49 ` Doug Anderson
2014-10-30 6:54 ` addy ke
2014-10-30 10:50 ` [PATCH] mmc: dw_mmc: add support for the other " Addy Ke
2014-10-30 11:02 ` Jaehoon Chung
2014-10-31 0:46 ` addy ke
2014-10-31 1:14 ` Jaehoon Chung
2014-10-30 11:11 ` Ulf Hansson
2014-10-30 11:17 ` Jaehoon Chung
2014-10-31 0:54 ` addy ke
2014-10-31 3:50 ` [PATCH v2] " Addy Ke
2014-10-31 5:14 ` Doug Anderson
2014-10-31 8:45 ` Jaehoon Chung
2014-10-31 15:55 ` Doug Anderson
2014-10-31 10:43 ` Heiko Stübner
2014-11-03 0:54 ` addy ke
2014-11-03 1:20 ` [PATCH v3] " Addy Ke
2014-11-03 8:59 ` Jaehoon Chung
2014-11-03 10:23 ` addy ke
2014-11-04 2:14 ` Jaehoon Chung
2014-11-03 10:23 ` Heiko Stübner
2014-11-04 2:15 ` Jaehoon Chung
2014-11-04 14:03 ` [PATCH v4] " Addy Ke
2014-11-11 4:02 ` [PATCH] mmc: dw_mmc: try pick the exact same voltage as vmmc for vqmmc Addy Ke
2014-11-11 8:52 ` Ulf Hansson
2014-11-12 18:04 ` Doug Anderson
2014-11-13 2:19 ` addy ke
2014-11-21 12:06 ` Ulf Hansson
2014-11-21 12:29 ` Jaehoon Chung
2014-11-21 17:42 ` Doug Anderson
2014-11-21 21:04 ` Doug Anderson
2014-11-24 13:29 ` Ulf Hansson
2014-11-25 2:38 ` Addy
2014-11-25 5:36 ` Doug Anderson
2014-11-25 21:11 ` Alexandru Stan
2014-11-25 5:29 ` Doug Anderson [this message]
2014-11-13 18:58 ` [PATCH v4] mmc: dw_mmc: add support for the other bit of sdio interrupt Doug Anderson
2014-11-14 13:25 ` Jaehoon Chung
2014-11-19 10:32 ` Ulf Hansson
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