Some eMMC chips have a boot partition that is meant to be used to load in low
level boot code.
This partition is available when the chip is powered up. Normally the boot
loader would disable
access to the partition once boot code was loaded in before passing control to
linux.
if booting occurs from another device (not the eMMC chip) the partition will
not be disabled by
the boot loader and control will be passed to linux. This will cause linux to
not recognize user
partitions on the chip unless access to the boot partition is deactivated.
See JEDEC Standard 84-A44 (eMMC 4.4 spec) -- Page 139
signed off by: Philip Rakity <prak...@marvell.com>
diff -ru linux-2.6.32.8/drivers/mmc/core/mmc.c linux-2.6.32.8
copy/drivers/mmc/core/mmc.c
--- linux-2.6.32.8/drivers/mmc/core/mmc.c 2010-02-09 04:57:19.000000000
-0800
+++ linux-2.6.32.8 copy/drivers/mmc/core/mmc.c 2010-03-12 20:56:16.000000000
-0800
@@ -430,6 +432,13 @@
}
/*
+ * ensure eMMC private booting PARTITION is not enabled
+ * see JEDEC Standard No. 84-A44 - Page 139
+ */
+ mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+ EXT_CSD_BOOT_CONFIG, 0x0);
+
+ /*
* Compute bus speed.
*/
max_dtr = (unsigned int)-1;
diff -ru linux-2.6.32.8/include/linux/mmc/mmc.h linux-2.6.32.8
copy/include/linux/mmc/mmc.h
--- linux-2.6.32.8/include/linux/mmc/mmc.h 2010-02-09 04:57:19.000000000
-0800
+++ linux-2.6.32.8 copy/include/linux/mmc/mmc.h 2010-03-12 20:53:48.000000000
-0800
@@ -251,6 +252,7 @@
* EXT_CSD fields
*/
+#define EXT_CSD_BOOT_CONFIG 179 /* R/W */
#define EXT_CSD_BUS_WIDTH 183 /* R/W */
#define EXT_CSD_HS_TIMING 185 /* R/W */
#define EXT_CSD_CARD_TYPE 196 /* RO */
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
