mmc: Allow forward compatibility for eMMC

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.

Change-Id: Ib69314bee902a4036183ef9a3565d9f0423ec971
Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index d4517603db46104e346e4ededf676606d4a2ed78..2a279463356f809428d05a4b3e6f49aa5c7312c2 100755 (executable)
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -293,13 +293,12 @@ 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];