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
>
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