From: Daniel Mack <daniel@caiaq.de>
Date: Thu, 1 Apr 2010 08:03:25 +0000 (+0200)
Subject: ARM: MXC: mxcmmc: work around a bug in the SDHC busy line handling
X-Git-Tag: v2.6.35-rc1~264^2~1^2~1^2~24
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3fcb027d7fd749569665d34a79ce2a8e00bc2ed6;p=pandora-kernel.git

ARM: MXC: mxcmmc: work around a bug in the SDHC busy line handling

MX3 SoCs have a silicon bug which corrupts CRC calculation of
multi-block transfers when connected SDIO peripheral doesn't drive the
BUSY line as required by the specs.

One way to prevent this is to only allow 1-bit transfers.

Another way is playing tricks with the DMA engine, but this isn't
mainline yet. So for now, we live with the performance drawback of 1-bit
transfers until a nicer solution is found.

This patch introduces a new host controller callback 'init_card' which
is for now only called from mmc_sdio_init_card().

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Volker Ernst <volker.ernst@txtr.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Michał Mirosław <mirqus@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---

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