On Thu, May 5, 2011 at 2:48 AM, Arindam Nath <arindam.nath@xxxxxxx> 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@xxxxxxx>
> Reviewed-by: Philip Rakity <prakity@xxxxxxxxxxx>
> Tested-by: Philip Rakity <prakity@xxxxxxxxxxx>
Acked-by: Zhangfei Gao<zhangfei.gao@xxxxxxxxxxx>
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
>
>
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