Re: [PATCH] MMC-4.5 Data Tag Support

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On Wed, Dec 21, 2011 at 1:09 PM, Saugata Das <saugata.das@xxxxxxxxxxxxxx> wrote:
> From: Saugata Das <saugata.das@xxxxxxxxxx>
>
> MMC-4.5 data tag feature will be used to store the file system meta-data in the
> tagged region of eMMC. This will improve the write and subsequent read transfer
> time for the meta data.
>
> Signed-off-by: Saugata Das <saugata.das@xxxxxxxxxx>
> ---
>  drivers/mmc/card/block.c |   17 +++++++++++++++--
>  drivers/mmc/core/mmc.c   |   14 ++++++++++++++
>  include/linux/mmc/card.h |    2 ++
>  include/linux/mmc/mmc.h  |    3 +++
>  4 files changed, 34 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index a1cb21f..af3b6c3 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -995,6 +995,7 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
>        struct mmc_blk_request *brq = &mqrq->brq;
>        struct request *req = mqrq->req;
>        struct mmc_blk_data *md = mq->data;
> +       bool do_data_tag;
>
>        /*
>         * Reliable writes are used to implement Forced Unit Access and
> @@ -1071,6 +1072,16 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
>                mmc_apply_rel_rw(brq, card, req);
>
>        /*
> +        * Data tag is used only during writing meta data to speed
> +        * up write and any subsequent read of this meta data
> +        */
> +       do_data_tag = (card->ext_csd.data_tag_unit_size) &&
> +               (req->cmd_flags & REQ_META) &&
> +               (rq_data_dir(req) == WRITE) &&
> +               ((brq->data.blocks * brq->data.blksz) >=
> +               card->ext_csd.data_tag_unit_size) ;
> +
> +       /*
>         * Pre-defined multi-block transfers are preferable to
>         * open ended-ones (and necessary for reliable writes).
>         * However, it is not sufficient to just send CMD23,
> @@ -1091,10 +1102,12 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
>
>        if ((md->flags & MMC_BLK_CMD23) &&
>            mmc_op_multi(brq->cmd.opcode) &&
> -           (do_rel_wr || !(card->quirks & MMC_QUIRK_BLK_NO_CMD23))) {
> +           (do_rel_wr || !(card->quirks & MMC_QUIRK_BLK_NO_CMD23) ||
> +               do_data_tag)) {
>                brq->sbc.opcode = MMC_SET_BLOCK_COUNT;
>                brq->sbc.arg = brq->data.blocks |
> -                       (do_rel_wr ? (1 << 31) : 0);
> +                       (do_rel_wr ? (1 << 31) : 0) |
> +                       (do_data_tag ? (1 << 29) : 0);
>                brq->sbc.flags = MMC_RSP_R1 | MMC_CMD_AC;
>                brq->mrq.sbc = &brq->sbc;
>        }
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index dbf421a..244049b 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -488,6 +488,20 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
>                        ext_csd[EXT_CSD_CACHE_SIZE + 1] << 8 |
>                        ext_csd[EXT_CSD_CACHE_SIZE + 2] << 16 |
>                        ext_csd[EXT_CSD_CACHE_SIZE + 3] << 24;
> +
> +               if (ext_csd[EXT_CSD_DATA_SECTOR_SIZE] == 1)
> +                       card->ext_csd.data_sector_size = 4096;
> +               else
> +                       card->ext_csd.data_sector_size = 512;
> +
> +               if ((ext_csd[EXT_CSD_DATA_TAG_SUPPORT] & 1) &&
> +                       (ext_csd[EXT_CSD_TAG_UNIT_SIZE] <= 8)) {
> +                       card->ext_csd.data_tag_unit_size =
> +                       ((unsigned int) 1 << ext_csd[EXT_CSD_TAG_UNIT_SIZE]) *
> +                       (card->ext_csd.data_sector_size);
> +               } else {
> +                       card->ext_csd.data_tag_unit_size = 0;
> +               }
>        }
>
>  out:
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index 415f2db..a55668d 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -71,6 +71,8 @@ struct mmc_ext_csd {
>        bool                    hpi_en;                 /* HPI enablebit */
>        bool                    hpi;                    /* HPI support bit */
>        unsigned int            hpi_cmd;                /* cmd used as HPI */
> +       unsigned int            data_sector_size;       /* 512Bytes or 4KB */
> +       unsigned int            data_tag_unit_size;     /* DATA TAG UNIT size */
>        u8                      raw_partition_support;  /* 160 */
>        u8                      raw_erased_mem_count;   /* 181 */
>        u8                      raw_ext_csd_structure;  /* 194 */
> diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
> index 0e71356..e076f7f 100644
> --- a/include/linux/mmc/mmc.h
> +++ b/include/linux/mmc/mmc.h
> @@ -273,6 +273,7 @@ struct _mmc_csd {
>  #define EXT_CSD_FLUSH_CACHE            32      /* W */
>  #define EXT_CSD_CACHE_CTRL             33      /* R/W */
>  #define EXT_CSD_POWER_OFF_NOTIFICATION 34      /* R/W */
> +#define EXT_CSD_DATA_SECTOR_SIZE       61      /* R */
>  #define EXT_CSD_GP_SIZE_MULT           143     /* R/W */
>  #define EXT_CSD_PARTITION_ATTRIBUTE    156     /* R/W */
>  #define EXT_CSD_PARTITION_SUPPORT      160     /* RO */
> @@ -313,6 +314,8 @@ struct _mmc_csd {
>  #define EXT_CSD_POWER_OFF_LONG_TIME    247     /* RO */
>  #define EXT_CSD_GENERIC_CMD6_TIME      248     /* RO */
>  #define EXT_CSD_CACHE_SIZE             249     /* RO, 4 bytes */
> +#define EXT_CSD_TAG_UNIT_SIZE          498     /* RO */
> +#define EXT_CSD_DATA_TAG_SUPPORT       499     /* RO */
>  #define EXT_CSD_HPI_FEATURES           503     /* RO */
>
>  /*
> --
> 1.7.4.3
>

I agree..
Reviewed-by: Venkatraman S <svenkatr@xxxxxx>
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