On 08/10/15 13:59, Ulf Hansson wrote:
> On 8 October 2015 at 09:09, Chaotian Jing <chaotian.jing@xxxxxxxxxxxx> wrote:
>> Suppose that we got a data crc error, and it triggers the mmc_reset.
>> mmc_reset will call mmc_send_status to see if HW reset was supported.
>> before issue CMD13, it will do retune, and if EMMC was in HS400 mode,
>> it will reduce frequency to 52Mhz firstly, then results in card init
>> was doing at 52Mhz.
>> The mmc_send_status was originally only done for mmc_test, so if retune
>> needed, do not call mmc_send_status.
>>
>> Signed-off-by: Chaotian Jing <chaotian.jing@xxxxxxxxxxxx>
>> Suggested-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
>> ---
>> drivers/mmc/card/mmc_test.c | 6 ++++++
>> drivers/mmc/core/mmc.c | 2 +-
>> 2 files changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/card/mmc_test.c b/drivers/mmc/card/mmc_test.c
>> index b78cf5d..2f78bfb 100644
>> --- a/drivers/mmc/card/mmc_test.c
>> +++ b/drivers/mmc/card/mmc_test.c
>> @@ -2272,6 +2272,12 @@ static int mmc_test_hw_reset(struct mmc_test_card *test)
>> if (!mmc_card_mmc(card) || !mmc_can_reset(card))
>> return RESULT_UNSUP_CARD;
>>
>> + if (host->need_retune) {
>> + pr_info("%s: cannot test hw reset because retune needed\n",
>> + mmc_hostname(test->card->host));
>> + return RESULT_FAIL;
>> + }
>> +
>> err = mmc_hw_reset(host);
>> if (!err)
>> return RESULT_OK;
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index e726903..647c96d 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -1938,7 +1938,7 @@ static int mmc_reset(struct mmc_host *host)
>> host->ops->hw_reset(host);
>>
>> /* If the reset has happened, then a status command will fail */
>> - if (!mmc_send_status(card, &status)) {
>> + if (!host->need_retune && !mmc_send_status(card, &status)) {
>
> No, this seem like the wrong solution! The main purpose of mmc_reset()
> is to try to reset and re-initiate the card, to make it operational
> again.
>
> I can't find a good reason to why we want to do a mmc_send_status() at
> this point, as even if it succeeds it will only tell us that the card
> has not been "hw-reset". No matter what, we should still try to make
> it fully operational again and thus give mmc_init_card() a try.
>
>>From this reasoning, I suggest we remove the call to mmc_send_status()
> from this path, as that will also address your issue with CRC errors
> in combination with re-tune.
Then you need to remove the hw_reset test from mmc_test. Refer:
http://marc.info/?l=linux-mmc&m=144360165906544&w=2
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