From: Aaron Lu <aaron.lu@amd.com>
To: Ulf Hansson <ulf.hansson@stericsson.com>
Cc: linux-mmc@vger.kernel.org, Chris Ball <cjb@laptop.org>,
Per Forlin <per.forlin@stericsson.com>,
Lee Jones <lee.jones@linaro.org>,
Stefan Nilsson XK <stefan.xk.nilsson@stericsson.com>
Subject: Re: [PATCH] mmc: core: Set correct bus mode before card init
Date: Fri, 16 Sep 2011 10:05:24 +0800 [thread overview]
Message-ID: <20110916020522.GA3691@lovegaga> (raw)
In-Reply-To: <1316101838-22660-1-git-send-email-ulf.hansson@stericsson.com>
Hi Ulf,
I'm not familiar with mmc, but I've some questions on sd below.
On Thu, Sep 15, 2011 at 05:50:38PM +0200, Ulf Hansson wrote:
> Earlier all cards where initiated with bus mode set as OPENDRAIN, and then
> later switched to PUSHPULL. According to the MMC/SD/SDIO specifications only
> MMC cards use OPENDRAIN during init. For both SD and SDIO the bus mode shall
> be PUSHPULL before attempting to init the card.
AFAIK, there is no open drain mode in sd, and the sd host controller
actually does not care about this setting(sdhci_set_ios does not
manipulate bus_mode stored in ios).
>
> The consequence of having incorrect bus mode can lead to not being able
> to detect the card. Therefore the default behavior have now been changed to
> PUSHPULL in mmc_power_up, and will only be temporarily switched when trying
> to attach or init a MMC card.
Do you see any sd cards that failed to be detected due to the incorrect
bus_mode setting?
Anyway, your patch removed an unnecessary call to mmc_set_bus_mode which
should have no effect if the underlying controller is sdhci.
-Aaron
next prev parent reply other threads:[~2011-09-16 2:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-15 15:50 [PATCH] mmc: core: Set correct bus mode before card init Ulf Hansson
2011-09-16 2:05 ` Aaron Lu [this message]
2011-09-16 6:57 ` Stefan Nilsson XK
2011-09-20 6:48 ` Linus Walleij
2011-09-21 18:20 ` Chris Ball
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