From: Matthew Garrett <mjg59@srcf.ucam.org>
To: linux-hotplug@vger.kernel.org
Subject: Autoloading of mmc_block for SD/MMC interfaces
Date: Tue, 31 Jan 2006 18:26:39 +0000 [thread overview]
Message-ID: <20060131182638.GA13475@srcf.ucam.org> (raw)
Hi,
Currently, mmc_block isn't autoloaded when an MMC or SD card is
inserted. On card insertion, /sys/bus/mmc/devices/mmc0:0001 (or similar)
is created. In this is a file called csd, which is a dump of 128 bits of
card specific data. According to drivers/mmc/mmc.c, the 12 bits starting
at bit 84 define the commands that the card will respond to.
include/linux/mmc/protocol.h specifies these - if bit 2 is set
(BLOCK_READ), then mmc_block should be loaded.
Sample dump:
tyrosine% cat /sys/bus/mmc/devices/mmc0:0001/csd
8c7f002a1f5983d3f6da8fff9e600000
^^^
12 bits - 0x95f
100101011111
^ CCC_BLOCK_READ
--
Matthew Garrett | mjg59@srcf.ucam.org
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next reply other threads:[~2006-01-31 18:26 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-31 18:26 Matthew Garrett [this message]
2006-01-31 18:34 ` Autoloading of mmc_block for SD/MMC interfaces Marco d'Itri
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