From: Marc Dietrich <marvin24@gmx.de>
To: Girish K S <girish.shivananjappa@linaro.org>
Cc: Saugata Das <saugata.das@linaro.org>,
Venkatraman S <svenkatr@ti.com>,
cjb@laptop.org, linux-mmc@vger.kernel.org,
Ulf Hansson <ulf.hansson@stericsson.com>,
Subhash Jadavani <subhashj@codeaurora.org>
Subject: Re: Re: [PATCH] mmc: core: Revert "skip card initialization if powerclass selection fails"
Date: Mon, 02 Jul 2012 13:20:20 +0200 [thread overview]
Message-ID: <4776161.gj4CVEvArs@fb07-iapwap2> (raw)
In-Reply-To: <CAGxe1ZHmm_UhkHmya63g_2YPrwZ+xwV1wdb5M5h44mxq82BvPg@mail.gmail.com>
Am Montag, 2. Juli 2012, 14:28:37 schrieb Girish K S:
> On 2 July 2012 14:23, Girish K S <girish.shivananjappa@linaro.org> wrote:
> > On 2 July 2012 14:13, Saugata Das <saugata.das@linaro.org> wrote:
> >> On 2 July 2012 12:26, Venkatraman S <svenkatr@ti.com> wrote:
> >>> This reverts commit 3d93576e(skip card initialization if
> >>> power class selection fails).
> >>> Problem has been reported when this is used with eMMC4.41
> >>> card with Tegra Platform. Till the issue is root caused,
> >>> bus width selection failure should not be treated as fatal.
> >>
> >> According to me, we need to find the root issue (which could be either
> >> host not able to provide enough current or faulty eMMC). Do we know,
> >> what could be the side effect of working on eMMC with less power than
> >> what it has requested in PWR_CL ?
> >>
> >> One known issue with the current power class selection is that we do
> >> not check the current requirement for a selected power class. It
> >> assumes that host is able to provide the maximum current needed at
> >> highest speed (> 800mA). Is it already checked on Tegra ?
> >
> > and at the least bus width i.e 1 bit mode.
>
> The MMC card spec has 2 max current values (power class) one for 4 bit
> mode and another for 8 bit mode at supported voltages. But the SDHCI
> spec has one MaxCur register for supported voltages but doesnt mention
> for which bus width. Any input on this is very helpful to resolve the
> powerclass issue that is pending
the higher nibble is for 8 bit and the lower one for 4 bit. The power class is
same for both bus width on this toshiba device.
Marc
next prev parent reply other threads:[~2012-07-02 11:20 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-02 6:56 [PATCH] mmc: core: Revert "skip card initialization if power class selection fails" Venkatraman S
2012-07-02 8:43 ` Saugata Das
2012-07-02 8:53 ` Girish K S
2012-07-02 8:58 ` Girish K S
2012-07-02 11:20 ` Marc Dietrich [this message]
2012-07-03 3:55 ` Re: [PATCH] mmc: core: Revert "skip card initialization if powerclass " Girish K S
2012-07-03 20:19 ` [PATCH] mmc: core: Revert "skip card initialization ifpowerclass " Marc Dietrich
2012-07-02 11:17 ` [PATCH] mmc: core: Revert "skip card initialization if powerclass " Marc Dietrich
2012-07-02 13:44 ` Saugata Das
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4776161.gj4CVEvArs@fb07-iapwap2 \
--to=marvin24@gmx.de \
--cc=cjb@laptop.org \
--cc=girish.shivananjappa@linaro.org \
--cc=linux-mmc@vger.kernel.org \
--cc=saugata.das@linaro.org \
--cc=subhashj@codeaurora.org \
--cc=svenkatr@ti.com \
--cc=ulf.hansson@stericsson.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox