diff options
| author | Avri Altman <avri.altman@wdc.com> | 2019-02-26 17:10:24 +0200 |
|---|---|---|
| committer | Ulf Hansson <ulf.hansson@linaro.org> | 2019-02-28 09:16:12 +0100 |
| commit | bc47e2f6f9e261ea07c678c3cad76eb5590c0fea (patch) | |
| tree | e92d2e8012ac4753e98ad828a9d8d6f96fb969c8 /drivers/mmc/core/sd.c | |
| parent | 85236d2be844ade0bd8b34e3626fc3e36498cd85 (diff) | |
mmc: core: Add discard support to sd
SD spec v5.1 adds discard support. The flows and commands are similar to
mmc, so just set the discard arg in CMD38.
A host which supports DISCARD shall check if the DISCARD_SUPPORT (b313)
is set in the SD_STATUS register. If the card does not support discard,
the host shall not issue DISCARD command, but ERASE command instead.
Post the DISCARD operation, the card may de-allocate the discarded
blocks partially or completely. So the host mustn't make any assumptions
concerning the content of the discarded region. This is unlike ERASE
command, in which the region is guaranteed to contain either '0's or
'1's, depends on the content of DATA_STAT_AFTER_ERASE (b55) in the scr
register.
One more important difference compared to ERASE is the busy timeout
which we will address on the next patch.
Signed-off-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc/core/sd.c')
| -rw-r--r-- | drivers/mmc/core/sd.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c index c2db94dab711..2b4fc2205b53 100644 --- a/drivers/mmc/core/sd.c +++ b/drivers/mmc/core/sd.c @@ -231,6 +231,8 @@ static int mmc_read_ssr(struct mmc_card *card) { unsigned int au, es, et, eo; __be32 *raw_ssr; + u32 resp[4] = {}; + u8 discard_support; int i; if (!(card->csd.cmdclass & CCC_APP_SPEC)) { @@ -276,7 +278,13 @@ static int mmc_read_ssr(struct mmc_card *card) } } - card->erase_arg = SD_ERASE_ARG; + /* + * starting SD5.1 discard is supported if DISCARD_SUPPORT (b313) is set + */ + resp[3] = card->raw_ssr[6]; + discard_support = UNSTUFF_BITS(resp, 313 - 288, 1); + card->erase_arg = (card->scr.sda_specx && discard_support) ? + SD_DISCARD_ARG : SD_ERASE_ARG; return 0; } |