linux-kernel - Re: [PATCH v2] mmc: core: Optimize the mmc erase size alignment

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Date:	Wed, 27 Jul 2016 18:02:43 +0800
From:	Baolin Wang <baolin.wang@...aro.org>
To:	Shawn Lin <shawn.lin@...k-chips.com>
Cc:	Ulf Hansson <ulf.hansson@...aro.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Russell King <rmk+kernel@....linux.org.uk>,
	Douglas Anderson <dianders@...omium.org>,
	Heiko Stübner <heiko@...ech.de>,
	David Jander <david@...tonic.nl>,
	Hans de Goede <hdegoede@...hat.com>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Mark Brown <broonie@...nel.org>,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v2] mmc: core: Optimize the mmc erase size alignment

On 27 July 2016 at 17:59, Shawn Lin <shawn.lin@...k-chips.com> wrote:
> On 2016/7/27 15:17, Baolin Wang wrote:
>>
>> Before issuing mmc_erase() function, users always have checked if it can
>> erase with mmc_can_erase/trim/discard() function, thus remove the
>> redundant
>> erase checking in mmc_erase() function.
>>
>> This patch also optimizes the erase start/end sector alignment with
>> round_up()/round_down() function, when erase command is MMC_ERASE_ARG.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
>> ---
>> Changes since v1:
>>  - Add the alignment if card->erase_size is not power of 2.
>> ---
>>  drivers/mmc/core/core.c |   78
>> +++++++++++++++++++++++++++++------------------
>>  1 file changed, 48 insertions(+), 30 deletions(-)
>>
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index b4c08d1a..303a917 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -2195,6 +2195,51 @@ out:
>>         return err;
>>  }
>>
>> +static unsigned int mmc_align_erase_size(struct mmc_card *card,
>> +                                        unsigned int *from,
>> +                                        unsigned int *to,
>> +                                        unsigned int nr)
>> +{
>> +       unsigned int from_new = *from, nr_new = nr, rem;
>> +
>> +       if (is_power_of_2(card->erase_size)) {
>> +               unsigned int temp = from_new;
>> +
>> +               from_new = round_up(temp, card->erase_size);
>> +               rem = from_new - temp;
>> +
>> +               if (nr_new > rem)
>> +                       nr_new -= rem;
>> +               else
>> +                       return 0;
>> +
>> +               nr_new = round_down(nr_new, card->erase_size);
>> +       } else {
>> +               rem = from_new % card->erase_size;
>> +               if (rem) {
>> +                       rem = card->erase_size - rem;
>> +                       from_new += rem;
>> +                       if (nr_new > rem)
>> +                               nr_new -= rem;
>> +                       else
>> +                               return 0;
>> +               }
>> +
>> +               rem = nr_new % card->erase_size;
>> +               if (rem)
>> +                       nr_new -= rem;
>> +       }
>> +
>> +       if (nr_new == 0)
>> +               return 0;
>> +
>> +       /* 'from' and 'to' are inclusive */
>> +       *to = from_new + nr_new - 1;
>> +       *from = from_new;
>> +
>> +       return nr_new;
>> +}
>> +
>>  /**
>>   * mmc_erase - erase sectors.
>>   * @card: card to erase
>> @@ -2210,13 +2255,6 @@ int mmc_erase(struct mmc_card *card, unsigned int
>> from, unsigned int nr,
>>         unsigned int rem, to = from + nr;
>>         int err;
>>
>> -       if (!(card->host->caps & MMC_CAP_ERASE) ||
>> -           !(card->csd.cmdclass & CCC_ERASE))
>
>
> Why remove the check , "!(card->csd.cmdclass & CCC_ERASE))"?

Cause we always issue mmc_can_erase() function before strating to do
mmc erase, so these looks like redundant.

>> -               return -EOPNOTSUPP;
>> -
>> -       if (!card->erase_size)
>> -               return -EOPNOTSUPP;
>> -
>>         if (mmc_card_sd(card) && arg != MMC_ERASE_ARG)
>>                 return -EOPNOTSUPP;
>>
>> @@ -2234,31 +2272,11 @@ int mmc_erase(struct mmc_card *card, unsigned int
>> from, unsigned int nr,
>>         }
>>
>>         if (arg == MMC_ERASE_ARG) {
>> -               rem = from % card->erase_size;
>> -               if (rem) {
>> -                       rem = card->erase_size - rem;
>> -                       from += rem;
>> -                       if (nr > rem)
>> -                               nr -= rem;
>> -                       else
>> -                               return 0;
>> -               }
>> -               rem = nr % card->erase_size;
>> -               if (rem)
>> -                       nr -= rem;
>> +               rem = mmc_align_erase_size(card, &from, &to, nr);
>> +               if (rem == 0)
>> +                       return 0;
>>         }
>>
>> -       if (nr == 0)
>> -               return 0;
>> -
>> -       to = from + nr;
>> -
>> -       if (to <= from)
>> -               return -EINVAL;
>> -
>> -       /* 'from' and 'to' are inclusive */
>> -       to -= 1;
>> -
>>         /*
>>          * Special case where only one erase-group fits in the timeout
>> budget:
>>          * If the region crosses an erase-group boundary on this
>> particular
>>
>
>
> --
> Best Regards
> Shawn Lin
>
> --
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-- 
Baolin.wang
Best Regards