Before issuing mmc_erase() function, users always have checked if it can
erase with mmc_can_erase/trim/discard() function, thus remove the redundant
erase checking in mmc_erase() function.

This patch also optimizes the erase start/end sector alignment with
round_up()/round_down() function, when erase command is MMC_ERASE_ARG.

Signed-off-by: Baolin Wang <baolin.w...@linaro.org>
---
Changes since v2:
 - Add nr checking and other optimization in mmc_erase() function.

Changes since v1:
 - Add the alignment if card->erase_size is not power of 2.
---
 drivers/mmc/core/core.c |   82 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 53 insertions(+), 29 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index e55cde6..52156d4 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2202,6 +2202,51 @@ out:
        return err;
 }
 
+static unsigned int mmc_align_erase_size(struct mmc_card *card,
+                                        unsigned int *from,
+                                        unsigned int *to,
+                                        unsigned int nr)
+{
+       unsigned int from_new = *from, nr_new = nr, rem;
+
+       if (is_power_of_2(card->erase_size)) {
+               unsigned int temp = from_new;
+
+               from_new = round_up(temp, card->erase_size);
+               rem = from_new - temp;
+
+               if (nr_new > rem)
+                       nr_new -= rem;
+               else
+                       return 0;
+
+               nr_new = round_down(nr_new, card->erase_size);
+       } else {
+               rem = from_new % card->erase_size;
+               if (rem) {
+                       rem = card->erase_size - rem;
+                       from_new += rem;
+                       if (nr_new > rem)
+                               nr_new -= rem;
+                       else
+                               return 0;
+               }
+
+               rem = nr_new % card->erase_size;
+               if (rem)
+                       nr_new -= rem;
+       }
+
+       if (nr_new == 0)
+               return 0;
+
+       /* 'from' and 'to' are inclusive */
+       *to = from_new + nr_new - 1;
+       *from = from_new;
+
+       return nr_new;
+}
+
 /**
  * mmc_erase - erase sectors.
  * @card: card to erase
@@ -2217,13 +2262,6 @@ int mmc_erase(struct mmc_card *card, unsigned int from, 
unsigned int nr,
        unsigned int rem, to = from + nr;
        int err;
 
-       if (!(card->host->caps & MMC_CAP_ERASE) ||
-           !(card->csd.cmdclass & CCC_ERASE))
-               return -EOPNOTSUPP;
-
-       if (!card->erase_size)
-               return -EOPNOTSUPP;
-
        if (mmc_card_sd(card) && arg != MMC_ERASE_ARG)
                return -EOPNOTSUPP;
 
@@ -2240,31 +2278,17 @@ int mmc_erase(struct mmc_card *card, unsigned int from, 
unsigned int nr,
                        return -EINVAL;
        }
 
-       if (arg == MMC_ERASE_ARG) {
-               rem = from % card->erase_size;
-               if (rem) {
-                       rem = card->erase_size - rem;
-                       from += rem;
-                       if (nr > rem)
-                               nr -= rem;
-                       else
-                               return 0;
-               }
-               rem = nr % card->erase_size;
-               if (rem)
-                       nr -= rem;
-       }
-
        if (nr == 0)
                return 0;
 
-       to = from + nr;
-
-       if (to <= from)
-               return -EINVAL;
-
-       /* 'from' and 'to' are inclusive */
-       to -= 1;
+       if (arg == MMC_ERASE_ARG) {
+               nr = mmc_align_erase_size(card, &from, &to, nr);
+               if (nr == 0)
+                       return 0;
+       } else {
+               /* 'from' and 'to' are inclusive */
+               to -= 1;
+       }
 
        /*
         * Special case where only one erase-group fits in the timeout budget:
-- 
1.7.9.5

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