Re: [PATCH v4 02/15] mmc: sd: query function modes for uhs cards

[zhangfei gao <zhangfei.gao@gmail.com>]

On Thu, May 5, 2011 at 2:48 AM, Arindam Nath <arindam.nath@amd.com> wrote:
> SD cards which conform to Physical Layer Spec v3.01 can support
> additional Bus Speed Modes, Driver Strength, and Current Limit
> other than the default values. We use CMD6 mode 0 to read these
> additional card functions. The values read here will be used
> during UHS-I initialization steps.
>
> Signed-off-by: Arindam Nath <arindam.nath@amd.com>
> Reviewed-by: Philip Rakity <prakity@marvell.com>
> Tested-by: Philip Rakity <prakity@marvell.com>

Acked-by: Zhangfei Gao<zhangfei.gao@marvell.com>
Verified with Toshiba uhs card and general hs card,   on mmp2 in SDMA mode.
> ---
>  drivers/mmc/core/sd.c    |   69 ++++++++++++++++++++++++++++++++++++++++-----
>  include/linux/mmc/card.h |    4 ++
>  2 files changed, 65 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index b0cd285..d4410c9 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -189,6 +189,9 @@ static int mmc_decode_scr(struct mmc_card *card)
>
>        scr->sda_vsn = UNSTUFF_BITS(resp, 56, 4);
>        scr->bus_widths = UNSTUFF_BITS(resp, 48, 4);
> +       if (scr->sda_vsn == SCR_SPEC_VER_2)
> +               /* Check if Physical Layer Spec v3.0 is supported*/
> +               scr->sda_spec3 = UNSTUFF_BITS(resp, 47, 1);
>
>        if (UNSTUFF_BITS(resp, 55, 1))
>                card->erased_byte = 0xFF;
> @@ -278,25 +281,75 @@ static int mmc_read_switch(struct mmc_card *card)
>                return -ENOMEM;
>        }
>
> +       /* Find out the supported Bus Speed Modes. */
>        err = mmc_sd_switch(card, 0, 0, 1, status);
>        if (err) {
> -               /* If the host or the card can't do the switch,
> -                * fail more gracefully. */
> +               /*
> +                * If the host or the card can't do the switch,
> +                * fail more gracefully.
> +                */
>                if ((err != -EINVAL)
> -                && (err != -ENOSYS)
> -                && (err != -EFAULT))
> +               && (err != -ENOSYS)
> +               && (err != -EFAULT))
>                        goto out;
>
> -               printk(KERN_WARNING "%s: problem reading switch "
> -                       "capabilities, performance might suffer.\n",
> +               printk(KERN_WARNING "%s: problem reading Bus Speed modes.\n",
>                        mmc_hostname(card->host));
>                err = 0;
>
>                goto out;
>        }
>
> -       if (status[13] & 0x02)
> -               card->sw_caps.hs_max_dtr = 50000000;
> +       if (card->scr.sda_spec3) {
> +               card->sw_caps.sd3_bus_mode = status[13];
> +
> +               /* Find out Driver Strengths supported by the card */
> +               err = mmc_sd_switch(card, 0, 2, 1, status);
> +               if (err) {
> +                       /*
> +                        * If the host or the card can't do the switch,
> +                        * fail more gracefully.
> +                        */
> +                       if ((err != -EINVAL)
> +                       && (err != -ENOSYS)
> +                       && (err != -EFAULT))
> +                               goto out;
> +
> +                       printk(KERN_WARNING "%s: problem reading "
> +                               "Driver Strength.\n",
> +                               mmc_hostname(card->host));
> +                       err = 0;
> +
> +                       goto out;
> +               }
> +
> +               card->sw_caps.sd3_drv_type = status[9];
> +
> +               /* Find out Current Limits supported by the card */
> +               err = mmc_sd_switch(card, 0, 3, 1, status);
> +               if (err) {
> +                       /*
> +                        * If the host or the card can't do the switch,
> +                        * fail more gracefully.
> +                        */
> +                       if ((err != -EINVAL)
> +                       && (err != -ENOSYS)
> +                       && (err != -EFAULT))
> +                               goto out;
> +
> +                       printk(KERN_WARNING "%s: problem reading "
> +                               "Current Limit.\n",
> +                               mmc_hostname(card->host));
> +                       err = 0;
> +
> +                       goto out;
> +               }
> +
> +               card->sw_caps.sd3_curr_limit = status[7];
> +       } else {
> +               if (status[13] & 0x02)
> +                       card->sw_caps.hs_max_dtr = 50000000;
> +       }
>
>  out:
>        kfree(status);
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index 72a9868..56f4d92 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -67,6 +67,7 @@ struct mmc_ext_csd {
>
>  struct sd_scr {
>        unsigned char           sda_vsn;
> +       unsigned char           sda_spec3;
>        unsigned char           bus_widths;
>  #define SD_SCR_BUS_WIDTH_1     (1<<0)
>  #define SD_SCR_BUS_WIDTH_4     (1<<2)
> @@ -80,6 +81,9 @@ struct sd_ssr {
>
>  struct sd_switch_caps {
>        unsigned int            hs_max_dtr;
> +       unsigned int            sd3_bus_mode;
> +       unsigned int            sd3_drv_type;
> +       unsigned int            sd3_curr_limit;
>  };
>
>  struct sdio_cccr {
> --
> 1.7.1
>
>