On 04/06/15 13:20, David Jander wrote:
> Signed-off-by: David Jander <david@xxxxxxxxxxx>
Please never send delta patches. Always send a new version of the whole patch.
> ---
> drivers/mmc/core/core.c | 28 +++++++++++++++++++++++++++-
> 1 file changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 6c9611b..b6aa9ad 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -2109,11 +2109,20 @@ int mmc_erase(struct mmc_card *card, unsigned int from, unsigned int nr,
> !(card->ext_csd.sec_feature_support & EXT_CSD_SEC_GB_CL_EN))
> return -EOPNOTSUPP;
>
> + /*
> + * Sanity check: If we do not erase aligned, whole erase-groups, return
> + * an error, since we intended a "secure" erase, silently not erasing
> + * something would be unacceptable.
> + */
I am not sure the value of a comment that can anyway be inferred from the code.
> if (arg == MMC_SECURE_ERASE_ARG) {
> if (from % card->erase_size || nr % card->erase_size)
> return -EINVAL;
> }
>
> + /*
> + * Make sure only erase-groups that are fully contained in the erase
> + * region are erased. Silently ignore the rest.
> + */
Ditto
> if (arg == MMC_ERASE_ARG) {
> rem = from % card->erase_size;
> if (rem) {
> @@ -2140,6 +2149,14 @@ int mmc_erase(struct mmc_card *card, unsigned int from, unsigned int nr,
> /* 'from' and 'to' are inclusive */
> to -= 1;
>
> + /*
> + * Special case where only one erase-group fits in the timout budget:
timout -> timeout
> + * If the region crosses an erase-group boundary on this particular
> + * case, we will be trimming more than one erase-group which, does not
> + * fit in the timeout budget of the controller, so we need to split it
> + * and call mmc_do_erase() twice if necessary. This special case is
> + * identified by the card->eg_boundary flag.
> + */
> if ((arg & MMC_TRIM_ARGS) && (card->eg_boundary) &&
> (from % card->erase_size)) {
> rem = card->erase_size - (from % card->erase_size);
> @@ -2244,7 +2261,16 @@ static unsigned int mmc_do_calc_max_discard(struct mmc_card *card,
> if (!qty)
> return 0;
>
> - /* We can only erase one erase group special case */
> + /*
> + * When specifying a sector range to trim, chances are we might cross
> + * an erase-group boundary even if the amount of sectors is less than
> + * one erase-group.
> + * If we can only fit one erase-group in the controller timeout budget,
> + * we have to care that erase-group boundaries are not crossed by a
> + * single trim operation. We flag that special case with "eg_boundary".
> + * In all other cases we can just decrement qty and pretend that we
> + * always touch (qty + 1) erase-groups as a simple optimization.
The language seems a little odd here. We are setting the max_discard limit
which does not involve "pretending" or "optimization", it is just a
calculation. The important point is that the calculation has to count the
maximum number of erase blocks affected not the size in erase blocks. You
could give an example e.g. if a 2 sector trim crosses an erase block
boundary then that counts as 2 erase blocks affected.
> + */
> if (qty == 1)
> card->eg_boundary = 1;
> else
>
--
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