Re: [PATCH]mmc: core: not to --qty when calculate timeout for SECURE_ERASE

[Adrian Hunter <adrian.hunter@intel.com>]

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@intel.com>
> ---
>  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@intel.com>
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@intel.com>
---
 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;
 }
-- 
1.7.6.5