[PATCH 3.12 65/78] mmc: Allow forward compatibility for eMMC

From: Jiri Slaby
Date: Fri Apr 22 2016 - 07:11:12 EST


From: Romain Izard <romain.izard.pro@xxxxxxxxx>

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

===============

commit 03a59437ef6b6ad7fb0165cb9b96c08d6bf057fc upstream.

As stated by the eMMC 5.0 specification, a chip should not be rejected
only because of the revision stated in the EXT_CSD_REV field of the
EXT_CSD register.

Remove the control on this value, the control of the CSD_STRUCTURE field
should be sufficient to reject future incompatible changes.

Signed-off-by: Romain Izard <romain.izard.pro@xxxxxxxxx>
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
drivers/mmc/core/mmc.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 6d02012a1d0b..36d6701de972 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -292,13 +292,12 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
}
}

+ /*
+ * The EXT_CSD format is meant to be forward compatible. As long
+ * as CSD_STRUCTURE does not change, all values for EXT_CSD_REV
+ * are authorized, see JEDEC JESD84-B50 section B.8.
+ */
card->ext_csd.rev = ext_csd[EXT_CSD_REV];
- if (card->ext_csd.rev > 7) {
- pr_err("%s: unrecognised EXT_CSD revision %d\n",
- mmc_hostname(card->host), card->ext_csd.rev);
- err = -EINVAL;
- goto out;
- }

card->ext_csd.raw_sectors[0] = ext_csd[EXT_CSD_SEC_CNT + 0];
card->ext_csd.raw_sectors[1] = ext_csd[EXT_CSD_SEC_CNT + 1];
--
2.8.1