[U-Boot] [PATCH RFC]: mmc: Add multi-block support

Lei Wen adrian.wenl at gmail.com
Sat Oct 16 04:37:41 CEST 2010


Hi Steve,

On Fri, Oct 15, 2010 at 6:12 AM, Steve Sakoman <steve at sakoman.com> wrote:
> From: Alagu Sankar <alagusankar at embwise.com>
>
> This patch adds multi-block read support for generic MMC. It also modifies
> existing multi-block write to limit the maximum number of blocks per transfer.
> A new member is added in the mmc structure for the host controller to specify
> the maximum number of blocks it supports.
>
> Signed-off-by: Alagu Sankar <alagusankar at embwise.com>
> Acked-by: Steve Sakoman <steve.sakoman at linaro.org>
> Tested-by: Steve Sakoman <steve.sakoman at linaro.org>
> ---
>
> This is a re-submission of Alagu's patch, modified only to remove the CONFIG
> option as requested in the earlier discussion of the patch:
>
> http://www.mail-archive.com/u-boot@lists.denx.de/msg32319.html
>
> I tested the patch on OMAP3 and OMAP4 and found no issues.  Sadly I did
> not see a performance improvement.
>
> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
> index c543d83..55975bb 100644
> --- a/drivers/mmc/mmc.c
> +++ b/drivers/mmc/mmc.c
> @@ -77,26 +77,16 @@ struct mmc *find_mmc_device(int dev_num)
>        return NULL;
>  }
>
> -static ulong
> -mmc_bwrite(int dev_num, ulong start, lbaint_t blkcnt, const void*src)
> +static int mmc_write_blocks(struct mmc *mmc, const char *src, uint start,
> +               uint blkcnt)
>  {
>        struct mmc_cmd cmd;
>        struct mmc_data data;
>        int err;
> -       int stoperr = 0;
> -       struct mmc *mmc = find_mmc_device(dev_num);
>        int blklen;
>
> -       if (!mmc)
> -               return -1;
> -
>        blklen = mmc->write_bl_len;
>
> -       if ((start + blkcnt) > mmc->block_dev.lba) {
> -               printf("MMC: block number 0x%lx exceeds max(0x%lx)",
> -                       start + blkcnt, mmc->block_dev.lba);
> -               return 0;
> -       }

You seems don't want this boudary check, but since it was merged as a
seperated patch
before, you should give your reason for remove this warning.

>        err = mmc_set_blocklen(mmc, mmc->write_bl_len);
>
>        if (err) {
> @@ -134,18 +124,46 @@ mmc_bwrite(int dev_num, ulong start, lbaint_t blkcnt, const void*src)
>                cmd.cmdarg = 0;
>                cmd.resp_type = MMC_RSP_R1b;
>                cmd.flags = 0;
> -               stoperr = mmc_send_cmd(mmc, &cmd, NULL);
> +               err = mmc_send_cmd(mmc, &cmd, NULL);
> +       }
> +
> +       return err;
> +}
> +
> +static ulong
> +mmc_bwrite(int dev_num, ulong start, lbaint_t blkcnt, const void *src)
> +{
> +       int err;
> +       int i;
> +       struct mmc *mmc = find_mmc_device(dev_num);
> +       uint b_max = mmc->b_max;
> +
> +       if (!mmc)
> +               return 0;
> +
> +       for (i = blkcnt; i > 0; i -= b_max) {
> +               uint blocks = (i > b_max) ? b_max : i;
> +
> +               err = mmc_write_blocks(mmc, src, start, blocks);
> +               if (err)
> +                       return blkcnt - i;
> +               start += blocks;
> +               src += (mmc->write_bl_len * blocks);
>        }
>
>        return blkcnt;
>  }
>
> -int mmc_read_block(struct mmc *mmc, void *dst, uint blocknum)
> +int mmc_read_blocks(struct mmc *mmc, void *dst, uint blocknum, uint blkcnt)
>  {
> +       int err;
>        struct mmc_cmd cmd;
>        struct mmc_data data;
>
> -       cmd.cmdidx = MMC_CMD_READ_SINGLE_BLOCK;
> +       if (blkcnt > 1)
> +               cmd.cmdidx = MMC_CMD_READ_MULTIPLE_BLOCK;
> +       else
> +               cmd.cmdidx = MMC_CMD_READ_SINGLE_BLOCK;
>
>        if (mmc->high_capacity)
>                cmd.cmdarg = blocknum;
> @@ -156,62 +174,22 @@ int mmc_read_block(struct mmc *mmc, void *dst, uint blocknum)
>        cmd.flags = 0;
>
>        data.dest = dst;
> -       data.blocks = 1;
> +       data.blocks = blkcnt;
>        data.blocksize = mmc->read_bl_len;
>        data.flags = MMC_DATA_READ;
>
> -       return mmc_send_cmd(mmc, &cmd, &data);
> -}
> -
> -int mmc_read(struct mmc *mmc, u64 src, uchar *dst, int size)
> -{
> -       char *buffer;
> -       int i;
> -       int blklen = mmc->read_bl_len;
> -       int startblock = lldiv(src, mmc->read_bl_len);
> -       int endblock = lldiv(src + size - 1, mmc->read_bl_len);
> -       int err = 0;
> -
> -       /* Make a buffer big enough to hold all the blocks we might read */
> -       buffer = malloc(blklen);
> -
> -       if (!buffer) {
> -               printf("Could not allocate buffer for MMC read!\n");
> -               return -1;
> -       }
> -
> -       /* We always do full block reads from the card */
> -       err = mmc_set_blocklen(mmc, mmc->read_bl_len);
> -
> +       err = mmc_send_cmd(mmc, &cmd, &data);
>        if (err)
> -               goto free_buffer;
> -
> -       for (i = startblock; i <= endblock; i++) {
> -               int segment_size;
> -               int offset;
> -
> -               err = mmc_read_block(mmc, buffer, i);
> -
> -               if (err)
> -                       goto free_buffer;
> -
> -               /*
> -                * The first block may not be aligned, so we
> -                * copy from the desired point in the block
> -                */
> -               offset = (src & (blklen - 1));
> -               segment_size = MIN(blklen - offset, size);
> -
> -               memcpy(dst, buffer + offset, segment_size);
> +               return err;
>
> -               dst += segment_size;
> -               src += segment_size;
> -               size -= segment_size;
> +       if (blkcnt > 1) {
> +               cmd.cmdidx = MMC_CMD_STOP_TRANSMISSION;
> +               cmd.cmdarg = 0;
> +               cmd.resp_type = MMC_RSP_R1b;
> +               cmd.flags = 0;
> +               err = mmc_send_cmd(mmc, &cmd, NULL);
>        }
>
> -free_buffer:
> -       free(buffer);
> -
>        return err;
>  }
>
> @@ -220,29 +198,26 @@ static ulong mmc_bread(int dev_num, ulong start, lbaint_t blkcnt, void *dst)
>        int err;
>        int i;
>        struct mmc *mmc = find_mmc_device(dev_num);
> +       uint b_max = mmc->b_max;
>
>        if (!mmc)
>                return 0;
>
> -       if ((start + blkcnt) > mmc->block_dev.lba) {
> -               printf("MMC: block number 0x%lx exceeds max(0x%lx)",
> -                       start + blkcnt, mmc->block_dev.lba);
> -               return 0;
> -       }

Same comments as above.

>        /* We always do full block reads from the card */
>        err = mmc_set_blocklen(mmc, mmc->read_bl_len);
> -
> -       if (err) {
> +       if (err)
>                return 0;
> -       }
>
> -       for (i = start; i < start + blkcnt; i++, dst += mmc->read_bl_len) {
> -               err = mmc_read_block(mmc, dst, i);
> +       for (i = blkcnt; i > 0; i -= b_max) {
> +               uint blocks = (i > b_max) ? b_max : i;
>
> +               err = mmc_read_blocks(mmc, dst, start, blocks);
>                if (err) {
>                        printf("block read failed: %d\n", err);
> -                       return i - start;
> +                       return blkcnt - i;
>                }
> +               start += blocks;
> +               dst += (mmc->read_bl_len * blocks);
>        }
>
>        return blkcnt;
> @@ -872,6 +847,9 @@ int mmc_register(struct mmc *mmc)
>        mmc->block_dev.block_read = mmc_bread;
>        mmc->block_dev.block_write = mmc_bwrite;
>
> +       if (mmc->b_max == 0)
> +               mmc->b_max = 1;
> +
>        INIT_LIST_HEAD (&mmc->link);
>
>        list_add_tail (&mmc->link, &mmc_devices);
> diff --git a/include/mmc.h b/include/mmc.h
> index 9f94f42..245e83a 100644
> --- a/include/mmc.h
> +++ b/include/mmc.h
> @@ -274,6 +274,7 @@ struct mmc {
>                        struct mmc_cmd *cmd, struct mmc_data *data);
>        void (*set_ios)(struct mmc *mmc);
>        int (*init)(struct mmc *mmc);
> +       uint b_max;
>  };
>
>  int mmc_register(struct mmc *mmc);
>
Generally, I like the idea to apply multi-read command for reading,
for it really coudl boost the performance
during booting. But considering I have post the silimar patch for only
do the change on the seperating write
command, could you rebase your multi-read patch on mine, and resend it?

Best regards,
Lei


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