Re: [PATCH v3 12/21] sd: emmc: add CMD21 tuning sequence

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Sai Pavan Boddu (sai.pavan.boddu@xilinx.com) wrote:
> eMMC cards support tuning sequence for entering HS200 mode.
> 
> Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
> ---
>  hw/sd/sd.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 47 insertions(+)
> 
> diff --git a/hw/sd/sd.c b/hw/sd/sd.c
> index bf963ec..174c28e 100644
> --- a/hw/sd/sd.c
> +++ b/hw/sd/sd.c
> @@ -1386,6 +1386,14 @@ static sd_rsp_type_t sd_normal_command(SDState *sd, SDRequest req)
>          }
>          break;
>  
> +    case 21:    /* CMD21: mmc SEND TUNING_BLOCK */
> +        if (sd->emmc && (sd->state == sd_transfer_state)) {
> +            sd->state = sd_sendingdata_state;
> +            sd->data_offset = 0;
> +            return sd_r1;
> +        }
> +        break;
> +
>      case 23:    /* CMD23: SET_BLOCK_COUNT */
>          if (sd->spec_version < SD_PHY_SPECv3_01_VERS) {
>              break;
> @@ -2120,6 +2128,30 @@ static const uint8_t sd_tuning_block_pattern[SD_TUNING_BLOCK_SIZE] = {
>      0xbb, 0xff, 0xf7, 0xff,         0xf7, 0x7f, 0x7b, 0xde,
>  };
>  
> +#define EXCSD_BUS_WIDTH_OFFSET 183
> +#define BUS_WIDTH_8_MASK    0x4
> +#define BUS_WIDTH_4_MASK    0x2
> +#define MMC_TUNING_BLOCK_SIZE   128
> +
> +static const uint8_t mmc_tunning_block_pattern[128] = {
> +       0xff, 0xff, 0x00, 0xff, 0xff, 0xff, 0x00, 0x00,
> +       0xff, 0xff, 0xcc, 0xcc, 0xcc, 0x33, 0xcc, 0xcc,
> +       0xcc, 0x33, 0x33, 0xcc, 0xcc, 0xcc, 0xff, 0xff,
> +       0xff, 0xee, 0xff, 0xff, 0xff, 0xee, 0xee, 0xff,
> +       0xff, 0xff, 0xdd, 0xff, 0xff, 0xff, 0xdd, 0xdd,
> +       0xff, 0xff, 0xff, 0xbb, 0xff, 0xff, 0xff, 0xbb,
> +       0xbb, 0xff, 0xff, 0xff, 0x77, 0xff, 0xff, 0xff,
> +       0x77, 0x77, 0xff, 0x77, 0xbb, 0xdd, 0xee, 0xff,
> +       0xff, 0xff, 0xff, 0x00, 0xff, 0xff, 0xff, 0x00,
> +       0x00, 0xff, 0xff, 0xcc, 0xcc, 0xcc, 0x33, 0xcc,
> +       0xcc, 0xcc, 0x33, 0x33, 0xcc, 0xcc, 0xcc, 0xff,
> +       0xff, 0xff, 0xee, 0xff, 0xff, 0xff, 0xee, 0xee,
> +       0xff, 0xff, 0xff, 0xdd, 0xff, 0xff, 0xff, 0xdd,
> +       0xdd, 0xff, 0xff, 0xff, 0xbb, 0xff, 0xff, 0xff,
> +       0xbb, 0xbb, 0xff, 0xff, 0xff, 0x77, 0xff, 0xff,
> +       0xff, 0x77, 0x77, 0xff, 0x77, 0xbb, 0xdd, 0xee,

Where does this magic pattern come from?  Is it part of some spec?

Dave

> +};
> +
>  uint8_t sd_read_byte(SDState *sd)
>  {
>      /* TODO: Append CRCs */
> @@ -2213,6 +2245,21 @@ uint8_t sd_read_byte(SDState *sd)
>          ret = sd_tuning_block_pattern[sd->data_offset++];
>          break;
>  
> +    case 21:    /* CMD21: SEND_TUNNING_BLOCK (MMC) */
> +        if (sd->data_offset >= MMC_TUNING_BLOCK_SIZE - 1) {
> +            sd->state = sd_transfer_state;
> +        }
> +        if (sd->ext_csd[EXCSD_BUS_WIDTH_OFFSET] & BUS_WIDTH_8_MASK) {
> +            ret = mmc_tunning_block_pattern[sd->data_offset++];
> +        } else {
> +            /* Return LSB Nibbles of two byte from the 8bit tuning block
> +             * for 4bit mode
> +             */
> +            ret = mmc_tunning_block_pattern[sd->data_offset++] & 0x0F;
> +            ret |= (mmc_tunning_block_pattern[sd->data_offset++] & 0x0F) << 4;
> +        }
> +        break;
> +
>      case 22:    /* ACMD22: SEND_NUM_WR_BLOCKS */
>          ret = sd->data[sd->data_offset ++];
>  
> -- 
> 2.7.4
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK