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mmc: core: Optimize the mmc erase size alignment

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In most cases the 'card->erase_size' is power of 2, then the round_up/down()
function is more efficient than '%' operation when the 'card->erase_size' is
power of 2.

Signed-off-by: Baolin Wang <[email protected]>
Tested-by: Shawn Lin <[email protected]>
Signed-off-by: Ulf Hansson <[email protected]>
This commit is contained in:
Baolin Wang 2016-09-07 10:38:25 +08:00 • committed by Ulf Hansson
commit 6c689886fb
1 changed files with 26 additions and 8 deletions
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34
drivers/mmc/core/core.c
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@ -2212,19 +2212,37 @@ static unsigned int mmc_align_erase_size(struct mmc_card *card,
{
unsigned int from_new = *from, nr_new = nr, rem;
rem = from_new % card->erase_size;
if (rem) {
rem = card->erase_size - rem;
from_new += rem;
/*
* When the 'card->erase_size' is power of 2, we can use round_up/down()
* to align the erase size efficiently.
*/
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;
}
rem = nr_new % card->erase_size;
if (rem)
nr_new -= rem;
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;