[ 120/150] mmc: core: expose RPMB partition only for CMD23 capable hosts

From: Greg Kroah-Hartman
Date: Tue Feb 26 2013 - 19:45:12 EST

3.8-stable review patch. If anyone has any objections, please let me know.


From: Balaji T K <balajitk@xxxxxx>

commit d0123ccac55088811bde4f76c4a3fdbd39c3cfba upstream.

SET_BLOCK_COUNT CMD23 is needed for all access to RPMB partition. If
block count is not set by CMD23, all subsequent read/write commands fail
as per eMMC specification. So, If the host does not support CMD23, do not
expose RPMB partition.

Accessing RPMB partition can cause hang / huge delay for hosts which do
not support CMD23.

Signed-off-by: Balaji T K <balajitk@xxxxxx>
Reported-and-Tested-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
Signed-off-by: Chris Ball <cjb@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/mmc/core/mmc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -496,7 +496,7 @@ static int mmc_read_ext_csd(struct mmc_c
* RPMB regions are defined in multiples of 128K.
card->ext_csd.raw_rpmb_size_mult = ext_csd[EXT_CSD_RPMB_MULT];
- if (ext_csd[EXT_CSD_RPMB_MULT]) {
+ if (ext_csd[EXT_CSD_RPMB_MULT] && mmc_host_cmd23(card->host)) {
mmc_part_add(card, ext_csd[EXT_CSD_RPMB_MULT] << 17,
"rpmb", 0, false,

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