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

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Message-ID: <dabf9f48-9b27-eb3f-1892-a1d416ed1d3b@rock-chips.com>
Date:	Wed, 27 Jul 2016 17:59:22 +0800
From:	Shawn Lin <shawn.lin@...k-chips.com>
To:	Baolin Wang <baolin.wang@...aro.org>, ulf.hansson@...aro.org
Cc:	shawn.lin@...k-chips.com, adrian.hunter@...el.com,
	rmk+kernel@....linux.org.uk, dianders@...omium.org,
	heiko@...ech.de, david@...tonic.nl, hdegoede@...hat.com,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
	broonie@...nel.org, linus.walleij@...aro.org
Subject: Re: [PATCH v2] mmc: core: Optimize the mmc erase size alignment

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))"?

> -		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