Re: [PATCH v2 1/2] mmc: core: Let sanitize timeout readable/writable via sysfs

[Ulf Hansson <ulf.hansson@linaro.org>]

On Thu, 1 Apr 2021 at 15:29, Bean Huo <huobean@gmail.com> wrote:
>
> From: Bean Huo <beanhuo@micron.com>
>
> As the density increases, the 4-minute timeout value for
> sanitize is no longer feasible. At the same time, devices
> of different densities have different timeout values, and it is
> difficult to obtain a unified standard timeout value. Therefore,
> it is better to let the user explicitly change  sanitize timeout
> value according to the eMMC density on the board.

This makes sense. The current timeout in the mmc core isn't good
enough. However, I think there is a better option than inventing a
sysfs node to allow userspace to specify the timeout.

First, we have the card quirks that the mmc core uses to allow us to
modify a common behaviour (in this case timeouts values for sanitize
operations). This can be used to enforce a specific timeout for the
eMMC card. I think this should take precedence over anything else.

Second, the ioctl command allows you to specify a specific command
timeout in the struct mmc_ioc_cmd (.cmd_timeout_ms). If this is
specified from user space we could forward it to mmc_santize() and use
that rather than the default MMC_SANITIZE_TIMEOUT_MS.

Would this satisfy your needs?

Kind regards
Uffe

>
> Signed-off-by: Bean Huo <beanhuo@micron.com>
> ---
>  drivers/mmc/core/mmc.c     | 34 ++++++++++++++++++++++++++++++++++
>  drivers/mmc/core/mmc_ops.c |  3 +--
>  include/linux/mmc/card.h   |  1 +
>  3 files changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 8741271d3971..3885cc1780ac 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -28,6 +28,7 @@
>
>  #define DEFAULT_CMD6_TIMEOUT_MS        500
>  #define MIN_CACHE_EN_TIMEOUT_MS 1600
> +#define MMC_SANITIZE_TIMEOUT_MS        (240 * 1000) /* 240s */
>
>  static const unsigned int tran_exp[] = {
>         10000,          100000,         1000000,        10000000,
> @@ -835,6 +836,37 @@ static ssize_t mmc_dsr_show(struct device *dev,
>
>  static DEVICE_ATTR(dsr, S_IRUGO, mmc_dsr_show, NULL);
>
> +static ssize_t sanitize_timeout_ms_show(struct device *dev,
> +                                       struct device_attribute *attr,
> +                                       char *buf)
> +{
> +       struct mmc_card *card = mmc_dev_to_card(dev);
> +
> +       return sysfs_emit(buf, "%d\n", card->sanitize_timeout_ms);
> +}
> +
> +static ssize_t sanitize_timeout_ms_store(struct device *dev,
> +                                        struct device_attribute *attr,
> +                                        const char *buf, size_t len)
> +{
> +       struct mmc_card *card = mmc_dev_to_card(dev);
> +       unsigned int new;
> +       int ret;
> +
> +       ret = kstrtouint(buf, 0, &new);
> +       if (ret < 0)
> +               return ret;
> +
> +       if (new == 0)
> +               return -EINVAL;
> +
> +       card->sanitize_timeout_ms = new;
> +
> +       return len;
> +}
> +static DEVICE_ATTR_RW(sanitize_timeout_ms);
> +
> +
>  static struct attribute *mmc_std_attrs[] = {
>         &dev_attr_cid.attr,
>         &dev_attr_csd.attr,
> @@ -861,6 +893,7 @@ static struct attribute *mmc_std_attrs[] = {
>         &dev_attr_rca.attr,
>         &dev_attr_dsr.attr,
>         &dev_attr_cmdq_en.attr,
> +       &dev_attr_sanitize_timeout_ms.attr,
>         NULL,
>  };
>  ATTRIBUTE_GROUPS(mmc_std);
> @@ -1623,6 +1656,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
>                 card->ocr = ocr;
>                 card->type = MMC_TYPE_MMC;
>                 card->rca = 1;
> +               card->sanitize_timeout_ms = MMC_SANITIZE_TIMEOUT_MS;
>                 memcpy(card->raw_cid, cid, sizeof(card->raw_cid));
>         }
>
> diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
> index f413474f0f80..40a4f9e22d30 100644
> --- a/drivers/mmc/core/mmc_ops.c
> +++ b/drivers/mmc/core/mmc_ops.c
> @@ -21,7 +21,6 @@
>
>  #define MMC_BKOPS_TIMEOUT_MS           (120 * 1000) /* 120s */
>  #define MMC_CACHE_FLUSH_TIMEOUT_MS     (30 * 1000) /* 30s */
> -#define MMC_SANITIZE_TIMEOUT_MS                (240 * 1000) /* 240s */
>
>  static const u8 tuning_blk_pattern_4bit[] = {
>         0xff, 0x0f, 0xff, 0x00, 0xff, 0xcc, 0xc3, 0xcc,
> @@ -1025,7 +1024,7 @@ int mmc_sanitize(struct mmc_card *card)
>         mmc_retune_hold(host);
>
>         err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_SANITIZE_START,
> -                        1, MMC_SANITIZE_TIMEOUT_MS);
> +                        1, card->sanitize_timeout_ms);
>         if (err)
>                 pr_err("%s: Sanitize failed err=%d\n", mmc_hostname(host), err);
>
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index f9ad35dd6012..9db0dcd9661e 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -273,6 +273,7 @@ struct mmc_card {
>
>         bool                    reenable_cmdq;  /* Re-enable Command Queue */
>
> +       unsigned int            sanitize_timeout_ms;
>         unsigned int            erase_size;     /* erase size in sectors */
>         unsigned int            erase_shift;    /* if erase unit is power 2 */
>         unsigned int            pref_erase;     /* in sectors */
> --
> 2.25.1
>