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+rene...@sang-engineering.com> >>> --- >>> 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. >