> -----Original Message-----
> From: Hunter, Adrian
> Sent: Monday, May 21, 2012 7:06 PM
> To: Dong, Chuanxiao
> Cc: linux-mmc@xxxxxxxxxxxxxxx; cjb@xxxxxxxxxx
> 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 <chuanxiao.dong@xxxxxxxxx>
> > ---
> > 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 <adrian.hunter@xxxxxxxxx>
> 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 <adrian.hunter@xxxxxxxxx>
> ---
> 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.
Thanks
Chuanxiao
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