[RESEND PATCH v1 1/1] mmc: fix response timeout after switch command

[Jaehoon Chung]

Hi Stefan,

On 1/29/21 4:23 AM, Stefan Bosch wrote:
> Hi,
> 
> On 27.01.21 00:38, Jaehoon Chung wrote:
>> Hi,
>>
>> On 1/23/21 9:37 PM, Stefan Bosch wrote:
>>> After issuing the switch command: Wait until 'current state' of the card
>>> status becomes 'tran'. This prevents from response timeout at the next
>>> command because of 'current state' = 'data'.>
>>> Signed-off-by: Stefan Bosch <stefan_b at posteo.net>
>>> ---
>>>
>>>   drivers/mmc/mmc.c | 3 ++-
>>>   include/mmc.h     | 1 +
>>>   2 files changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
>>> index a47700e313..8ccd2058a9 100644
>>> --- a/drivers/mmc/mmc.c
>>> +++ b/drivers/mmc/mmc.c
>>> @@ -823,7 +823,8 @@ static int __mmc_switch(struct mmc *mmc, u8 set, u8 index, u8 value,
>>>                    value);
>>>               return -EIO;
>>>           }
>>> -        if (!ret && (status & MMC_STATUS_RDY_FOR_DATA))
>>> +        if (!ret && (status & MMC_STATUS_RDY_FOR_DATA) &&
>>> +            (status & MMC_STATUS_CURR_STATE) == MMC_STATE_TRANS)
>>
>> AFAIK, MMC_STATUS_RDY_FOR_DATA bit means the signaling about "buffer is empty".
>> Even though its bit was set, does it need to check TRANS state?
>>
>> Best Regards,
>> Jaehoon Chung
>>
> 
> After issuing command 'MMC_CMD_SWITCH' = CMD6 the state transits to 'DATA'. But in DATA state it is not possible to issue a (new) CMD except CMD12 (operation complete) and CMD7 (select/deselect card). See appropriate State Diagram, e.g. "Figure 4-3: SD Memory Card State Diagram (data transfer mode)" in "SD Specifications Part 1 - Physical Layer - Simplified Specification - Version 2.00". Status 'Ready For Data' is in my opinion only relevant for CMD12 and CMD7.

Thanks for explanation. I have checked Spec about SD and eMMC. It makes sense.

Reviewed-by: Jaehoon Chung <jh80.chung at samsung.com>

Best Regards,
Jaehoon Chung


> 
> Regards
> Stefan Bosch
> 
>>>               return 0;
>>>           udelay(100);
>>>       } while (get_timer(start) < timeout_ms);
>>> diff --git a/include/mmc.h b/include/mmc.h
>>> index 1d377e0281..18402494c6 100644
>>> --- a/include/mmc.h
>>> +++ b/include/mmc.h
>>> @@ -178,6 +178,7 @@ static inline bool mmc_is_tuning_cmd(uint cmdidx)
>>>   #define MMC_STATUS_ERROR    (1 << 19)
>>>     #define MMC_STATE_PRG        (7 << 9)
>>> +#define MMC_STATE_TRANS        (4 << 9)
>>>     #define MMC_VDD_165_195        0x00000080    /* VDD voltage 1.65 - 1.95 */
>>>   #define MMC_VDD_20_21        0x00000100    /* VDD voltage 2.0 ~ 2.1 */
>>>
>>
>