On 21/05/12 14:19, Dong, Chuanxiao wrote: > > >> -----Original Message----- >> From: Hunter, Adrian >> Sent: Monday, May 21, 2012 7:06 PM >> To: Dong, Chuanxiao >> Cc: [email protected]; [email protected] >> Subject: Re: [PATCH]mmc: core: not to --qty when calculate timeout for >> SECURE_ERASE >> >> On 13/04/12 07:19, Chuanxiao Dong wrote: >>> --qty when calculating erase timeout for trim/erase & secure >>> trim/erase can prevent the erase range crossing qty+1 erase groups, >>> which made the final timeout value is too large for the host. >>> >>> When operate SECURE_ERASE, driver needs the erase range is aligned >>> with erase size, otherwise do nothing and return an error. That is to >>> say it is not necessary for SECURE_ERASE to --qty since it will never >>> cross an erase group. >>> >>> Signed-off-by: Chuanxiao Dong <[email protected]> >>> --- >>> drivers/mmc/core/core.c | 9 ++++++++- >>> 1 files changed, 8 insertions(+), 1 deletions(-) >>> >>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index >>> e541efb..b5a393a 100644 >>> --- a/drivers/mmc/core/core.c >>> +++ b/drivers/mmc/core/core.c >>> @@ -1761,7 +1761,7 @@ static unsigned int mmc_do_calc_max_discard(struct >> mmc_card *card, >>> if (!qty) >>> return 0; >>> >>> - if (qty == 1) >>> + if (qty == 1 && arg != MMC_SECURE_ERASE_ARG) >>> return 1; >> >> arg is never MMC_SECURE_ERASE_ARG >> >>> >>> /* Convert qty to sectors */ >>> @@ -1772,6 +1772,13 @@ static unsigned int mmc_do_calc_max_discard(struct >> mmc_card *card, >>> else >>> max_discard = --qty * card->erase_size; >>> >>> + /* >>> + * since SECURE_ERASE is erase group aligned, otherwise >>> + * it cannot be erased in secure purpose, needn't --qty >>> + */ >>> + if (arg == MMC_SECURE_ERASE_ARG) >>> + max_discard += card->erase_size; >>> + >>> return max_discard; >>> } >>> >> >> What about: >> >> From: Adrian Hunter <[email protected]> >> Date: Mon, 21 May 2012 13:32:42 +0300 >> Subject: [PATCH] mmc: core: fix max_discard calculation >> >> The maximum discard calculation was unnecessarily pessimistic in the case of >> erasing entire erase groups. In that case, the quantity does not need to be >> decreased by 1 to allow for misalignment because the erasure is always >> aligned to >> whole erase groups. >> >> Signed-off-by: Adrian Hunter <[email protected]> >> --- >> drivers/mmc/core/core.c | 22 +++++++++++++++++----- >> 1 files changed, 17 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index >> 0b6141d..36bfdce 100644 >> --- a/drivers/mmc/core/core.c >> +++ b/drivers/mmc/core/core.c >> @@ -1742,7 +1742,7 @@ static unsigned int mmc_do_calc_max_discard(struct >> mmc_card *card, { >> struct mmc_host *host = card->host; >> unsigned int max_discard, x, y, qty = 0, max_qty, timeout; >> - unsigned int last_timeout = 0; >> + unsigned int last_timeout = 0, aligned_qty; >> >> if (card->erase_shift) >> max_qty = UINT_MAX >> card->erase_shift; @@ -1769,16 +1769,28 @@ >> static unsigned int mmc_do_calc_max_discard(struct mmc_card *card, >> if (!qty) >> return 0; >> >> - if (qty == 1) >> - return 1; >> + if (arg & MMC_TRIM_ARGS) { >> + /* >> + * The requested number of sectors may not be aligned to an >> + * erase group, so we have to decrease the quantity by 1 (unless >> + * it is 1) e.g. trimming 2 sectors could cause 2 erase groups >> + * to be affected even though 2 sectors is less than the size of >> + * 1 erase group. >> + */ >> + if (qty == 1) >> + return 1; >> + aligned_qty = qty - 1; >> + } else { >> + aligned_qty = qty; >> + } >> >> /* Convert qty to sectors */ >> if (card->erase_shift) >> - max_discard = --qty << card->erase_shift; >> + max_discard = aligned_qty << card->erase_shift; >> else if (mmc_card_sd(card)) >> max_discard = qty; >> else >> - max_discard = --qty * card->erase_size; >> + max_discard = aligned_qty * card->erase_size; >> >> return max_discard; >> } > > Hi Hunter, > Your patch looks good to me. > > Since you also mentioned that the arg will never be MMC_SECURE_ERASE_ARG, I > want to know why not calculate erase size for secure trim/erase operations? > As specification said, secure trim/erase operations has different timeout > value with trim/erase.
There are 2 problems. First, there is only 1 value for maximum discard whether secure or not. Secondly, the timeout for secure erase can be so great that any quantity exceeds the maximum timeout. > > Thanks > Chuanxiao > > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
