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

[Raffaele Recalcati]

On Thu, Mar 10, 2011 at 5:29 PM, Lei Wen <adrian.wenl at gmail.com> wrote:
> 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
>

Look at JEDEC Standard No. 84-A441 document at page 190.
It is normal to ask the card capabilities before setting.
But I understand also that in your case there is some issue.
I'm sorry, what does "multi-time" mean?

Thx,
Raffaele


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