RE: [PATCH] mmc-utils: Add softreset command for issuing CMD0

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Hi,

> 
> CMD0 may be used to see if the hardware can handle a UHS card
> that completed the voltage switch. If a UHS card has problems
> coming back up after CMD0 your hardware may not support a hard
> reset properly.
I think it's a useful addition, not just for that reason.
Specifically to test hw-reset support, I think you should use the GO_PRE_IDLE_STATE option.

> 
> Signed-off-by: Christian Loehle <cloehle@xxxxxxxxxxxxxx>
> ---
>  mmc.c      |  5 +++++
>  mmc.h      |  3 +++
>  mmc_cmds.c | 30 ++++++++++++++++++++++++++++++
>  mmc_cmds.h |  1 +
>  4 files changed, 39 insertions(+)
> 
> diff --git a/mmc.c b/mmc.c
> index 6c56387..ba2c883 100644
> --- a/mmc.c
> +++ b/mmc.c
> @@ -245,6 +245,11 @@ static struct Command commands[] = {
>                 "be 1.",
>         NULL
>         },
> +       { do_soft_reset, -1,
> +         "softreset", "<device>\n"
> +         "Issues a CMD0 softreset, e.g. for testing if hardware reset for UHS
> works\n\n",
> +         NULL
> +       },
>         { 0, 0, 0, 0 }
>  };
> 
> diff --git a/mmc.h b/mmc.h
> index daff62c..9796d2e 100644
> --- a/mmc.h
> +++ b/mmc.h
> @@ -21,6 +21,7 @@
>  #include <linux/mmc/ioctl.h>
> 
>  /* From kernel linux/mmc/mmc.h */
> +#define MMC_GO_IDLE_STATE         0   /* bc                          */
>  #define MMC_SWITCH             6       /* ac   [31:0] See below        R1b */
>  #define MMC_SEND_EXT_CSD       8       /* adtc                         R1  */
>  #define MMC_SEND_STATUS                13      /* ac   [31:16] RCA        R1  */
> @@ -226,6 +227,7 @@
> 
> 
>  /* From kernel linux/mmc/core.h */
> +#define MMC_RSP_NONE   0                       /* no response */
>  #define MMC_RSP_PRESENT        (1 << 0)
>  #define MMC_RSP_136    (1 << 1)                /* 136 bit response */
>  #define MMC_RSP_CRC    (1 << 2)                /* expect valid crc */
> @@ -234,6 +236,7 @@
> 
>  #define MMC_CMD_AC     (0 << 5)
>  #define MMC_CMD_ADTC   (1 << 5)
> +#define MMC_CMD_BC     (2 << 5)
> 
>  #define MMC_RSP_SPI_S1 (1 << 7)                /* one status byte */
>  #define MMC_RSP_SPI_BUSY (1 << 10)             /* card may send busy */
> diff --git a/mmc_cmds.c b/mmc_cmds.c
> index 12b7802..c027cfa 100644
> --- a/mmc_cmds.c
> +++ b/mmc_cmds.c
> @@ -3039,3 +3039,33 @@ out:
>         close(dev_fd);
>         return ret;
>  }
> +
> +int do_soft_reset(int nargs, char **argv)
> +{
> +       int fd;
> +       char *device;
> +       struct mmc_ioc_cmd idata;
> +
> +       if (nargs != 2) {
> +               fprintf(stderr, "Usage: mmc status softreset
> </path/to/mmcblkX>\n");
> +               exit(1);
> +       }
> +
> +       device = argv[1];
> +
> +       fd = open(device, O_RDWR);
> +       if (fd < 0) {
> +               perror("open");
> +               exit(1);
> +       }
> +
> +       memset(&idata, 0, sizeof(idata));
> +       idata.opcode = MMC_GO_IDLE_STATE;
> +       idata.flags = MMC_RSP_NONE | MMC_CMD_BC;
How about adding all 3 flavors of soft-reset: GO_IDLE_STATE, GO_PRE_IDLE_STATE, and BOOT_INITIATION.
There can be 3 different command, that calls the same __soft_reset helper, or whatever.
What do you think?  

Thanks,
Avri

> +
> +       /* No need to check for error, it is expected */
> +       ioctl(fd, MMC_IOC_CMD, &idata);
> +       close(fd);
> +
> +       return 0;
> +}
> diff --git a/mmc_cmds.h b/mmc_cmds.h
> index 0f7c004..c112a95 100644
> --- a/mmc_cmds.h
> +++ b/mmc_cmds.h
> @@ -47,3 +47,4 @@ int do_read_cid(int argc, char **argv);
>  int do_read_csd(int argc, char **argv);
>  int do_erase(int nargs, char **argv);
>  int do_general_cmd_read(int nargs, char **argv);
> +int do_soft_reset(int nargs, char **argv);
> --
> 2.36.1
> 
> Hyperstone GmbH | Reichenaustr. 39a  | 78467 Konstanz
> Managing Director: Dr. Jan Peter Berns.
> Commercial register of local courts: Freiburg HRB381782





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