[U-Boot] [RFC 2/3][v2] mmc: SEND_OP_COND considers card capabilities (voltage)

[Lei Wen]

Hi Raffaele,

On Thu, Mar 10, 2011 at 11:43 PM, Raffaele Recalcati
<lamiaposta71 at gmail.com> wrote:
> From: Raffaele Recalcati <raffaele.recalcati at bticino.it>
>
> The first SEND_OP_COND (CMD1) is used only to ask card capabilities, waiting
> that the card is not busy.
> After it, an AND operation is done between card capabilities and host
> capabilities, (at the moment only for the voltage field).
> Finally the correct value is sent to the MMC.
>
> Signed-off-by: Raffaele Recalcati <raffaele.recalcati at bticino.it>
> ---
>  drivers/mmc/mmc.c |   21 +++++++++++++++++++--
>  include/mmc.h     |    2 ++
>  2 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
> index 042653f..ded630b 100644
> --- a/drivers/mmc/mmc.c
> +++ b/drivers/mmc/mmc.c
> @@ -347,17 +347,34 @@ sd_send_op_cond(struct mmc *mmc)
>
>  int mmc_send_op_cond(struct mmc *mmc)
>  {
> -       int timeout = 1000;
> +       int timeout = 10000;
>        struct mmc_cmd cmd;
>        int err;
>
>        /* Some cards seem to need this */
>        mmc_go_idle(mmc);
>
> +       /* Asking to the card its capabilities */
> +       do {
> +               cmd.cmdidx = MMC_CMD_SEND_OP_COND;
> +               cmd.resp_type = MMC_RSP_R3;
> +               cmd.cmdarg = 0;
> +               cmd.flags = 0;
> +
> +               err = mmc_send_cmd(mmc, &cmd, NULL);
> +
> +               if (err)
> +                       return err;
> +
> +               udelay(1000);
> +       } while (!(cmd.response[0] & OCR_BUSY) && timeout--);

I think you should not put the first probe a multi-time. In linux framework,
it would skip the first probing.

I test with this patch and fail to detect my emmc card...
While just let the first probe once, it works fine.

Best regards,
Lei