On 09/21/2016 03:00 PM, Wolfram Sang wrote:
> On Tue, Sep 20, 2016 at 06:25:37PM +0900, Jaehoon Chung wrote:
>> Hi Wolfram,
>>
>> On 09/20/2016 05:57 AM, Wolfram Sang wrote:
>>> The core uses it for polling. Give drivers a proper define handle this
>>> case like for other response types.
>>>
>>> Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
>>> ---
>>> include/linux/mmc/core.h | 3 +++
>>> 1 file changed, 3 insertions(+)
>>>
>>> diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
>>> index b01e77de1a74de..4caee099b63a28 100644
>>> --- a/include/linux/mmc/core.h
>>> +++ b/include/linux/mmc/core.h
>>> @@ -55,6 +55,9 @@ struct mmc_command {
>>> #define MMC_RSP_R6 (MMC_RSP_PRESENT|MMC_RSP_CRC|MMC_RSP_OPCODE)
>>> #define MMC_RSP_R7 (MMC_RSP_PRESENT|MMC_RSP_CRC|MMC_RSP_OPCODE)
>>>
>>> +/* Can be used by core to poll after switch to MMC HS mode */
>>> +#define MMC_RSP_R1_NO_CRC (MMC_RSP_PRESENT|MMC_RSP_OPCODE)
>>
>> MMC_RSP_RQ_NO_CRC is described at Specification?
>
> Yes. JEDEC eMMC Spec v5.1, chapter 6.6.2, in the note:
>
> "NOTE While the actual timing change is done, the behavior of any
> command sent (like CMD13) cannot be guaranteed due to the asynchronous
> operation. Therefore it is not recommended to use CMD13 to check the
> busy completion of the timing change indication. In case CMD13 is used
> the host must ignore CRC errors, if appear."
Thanks for noticing this. I read the spec again.
Best Regards,
Jaehoon Chung
>
> And the MMC core does that. In mmc_ops.c:
>
> 70 if (ignore_crc)
> 71 cmd.flags &= ~MMC_RSP_CRC;
>
> And ignore_crc is used in mmc.c (last 'true' parameter):
>
> 1023 err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> 1024 EXT_CSD_HS_TIMING, EXT_CSD_TIMING_HS,
> 1025 card->ext_csd.generic_cmd6_time,
> 1026 true, false, true);
>
> This is why I put the comment above the define.
>
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