From: Pierre Ossman <drzeus-mmc@drzeus.cx>
To: "Bryan Wu" <cooloney.lkml@gmail.com>
Cc: "Mike Frysinger" <vapier.adi@gmail.com>,
"Cai, Cliff" <Cliff.Cai@analog.com>,
linux-kernel@vger.kernel.org
Subject: Re: [patch] split MMC_CAP_4_BIT_DATA
Date: Fri, 11 Jan 2008 12:18:55 +0100 [thread overview]
Message-ID: <20080111121855.4dba2a97@poseidon.drzeus.cx> (raw)
In-Reply-To: <386072610801110222r28e66cb7i6cadb41bf565b3b4@mail.gmail.com>
On Fri, 11 Jan 2008 18:22:14 +0800
"Bryan Wu" <cooloney.lkml@gmail.com> wrote:
>
> I guess it is for MMC/SD card insert detection. Is it related with the
> 4-bit MMC and 4-bit SD?
> Actually, there are some issues about the card insert detection on
> BF54x SDH. Following is some comments of our bfin-sdh driver which is
> in the development.
>
Right. As you've noticed, that pin is not a reliable way of detecting cards. It works badly, if all, for MMC cards. And some SD cards also lack the necessary pull-up.
But for the matter at hand, some cards might rely on the pull-up being there, so you'll get bit-errors without it. I don't have time to double check the specs right now, but it might explain why you're seeing problems with MMC and not SD.
Btw, the MMC core sends you ios information on how you should fiddle with that bit. It was needed on a Winbond controller (the wbsd driver) as some models relied on it for card detection.
Rgds
--
-- Pierre Ossman
Linux kernel, MMC maintainer http://www.kernel.org
PulseAudio, core developer http://pulseaudio.org
rdesktop, core developer http://www.rdesktop.org
next prev parent reply other threads:[~2008-01-11 11:19 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-08 18:29 Mike Frysinger
2008-01-08 19:21 ` Pierre Ossman
2008-01-08 19:40 ` Mike Frysinger
2008-01-08 20:49 ` Pierre Ossman
2008-01-08 21:44 ` Mike Frysinger
2008-01-09 7:21 ` Pierre Ossman
2008-01-09 2:32 ` Bryan Wu
2008-01-09 3:21 ` Cai, Cliff
2008-01-09 7:23 ` Pierre Ossman
2008-01-09 16:45 ` Bryan Wu
2008-01-10 8:54 ` Pierre Ossman
2008-01-10 9:22 ` Bryan Wu
2008-01-10 11:57 ` Pierre Ossman
2008-01-11 6:17 ` Bryan Wu
2008-01-11 6:25 ` Mike Frysinger
2008-01-11 8:40 ` Pierre Ossman
2008-01-11 9:08 ` Mike Frysinger
2008-01-11 9:35 ` Pierre Ossman
2008-01-11 9:47 ` Mike Frysinger
2008-01-11 10:05 ` Pierre Ossman
2008-01-11 10:22 ` Bryan Wu
2008-01-11 11:18 ` Pierre Ossman [this message]
2008-01-11 17:52 ` Robin Getz
2008-01-12 13:02 ` Robin Getz
2008-01-12 15:24 ` Bryan Wu
2008-01-12 15:39 ` Pierre Ossman
2008-01-09 4:23 ` Bryan Wu
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