Hi Raffaele,
On Fri, Mar 11, 2011 at 2:30 PM, Raffaele Recalcati
<lamiapost...@gmail.com> wrote:
> On Fri, Mar 11, 2011 at 4:14 AM, Lei Wen <adrian.w...@gmail.com> wrote:
>> On Fri, Mar 11, 2011 at 12:59 AM, Raffaele Recalcati
>> <lamiapost...@gmail.com> wrote:
>>> On Thu, Mar 10, 2011 at 5:29 PM, Lei Wen <adrian.w...@gmail.com> wrote:
>>>> Hi Raffaele,
>>>>
>>>> On Thu, Mar 10, 2011 at 11:43 PM, Raffaele Recalcati
>>>> <lamiapost...@gmail.com> wrote:
>>>>> From: Raffaele Recalcati <raffaele.recalc...@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.recalc...@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?
>>>
>>
>> I mean on my board I cannot get (!(cmd.response[0] & OCR_BUSY) to be
>> true for the first
>> MMC_CMD_SEND_OP_COND until its timeout, which lead to card init fail.
>>
>> Best regards,
>> Lei
>>
>
> This means 10msec are not enough.
> Even if a board dependent value should be better, can you find please
> the minimum value that it nice for your board?
It is not about the delay, it is about you shouldn't let the probe
perform multi-times.
As you also mention the JESD84-A44 doc, you could see the query mode only
perform _ONCE_, then continue to send SEND_OP_COND till card accept that.
So my point is that: in this patch, you shouldn't add a do{} while for
the first query.
Please remove it. As I test, my board works fine with the do{} while remove.
Best regards,
Lei
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