RE: [PATCH 1/2] mmc-utils: introduce optional --verify argument for 'extcsd write'

[Avri Altman <Avri.Altman@wdc.com>]

 
> Registers can be write-once but ioctl does not necessarily return with an
> error. Thus it is a good idea to allow verifying the data written.
Yeah - I find this approach more practical, than e.g. analyze the R1b response.

> 
> Signed-off-by: Enrico Jorns <ejo@pengutronix.de>
Aked-by: Avri Altman <avri.altman@wdc.com>

> ---
>  mmc.c      |  7 ++++---
>  mmc_cmds.c | 28 ++++++++++++++++++++++++++--
>  2 files changed, 30 insertions(+), 5 deletions(-)
> 
> diff --git a/mmc.c b/mmc.c
> index 795b4e3..3f813b4 100644
> --- a/mmc.c
> +++ b/mmc.c
> @@ -56,9 +56,10 @@ static struct Command commands[] = {
>                 "Print extcsd data from <device>.",
>           NULL
>         },
> -       { do_write_extcsd, 3,
> -         "extcsd write", "<offset> <value> <device>\n"
> -                 "Write <value> at offset <offset> to <device>'s extcsd.",
> +       { do_write_extcsd, -3,
> +         "extcsd write", "<offset> <value> <device> [--verify]\n"
> +                 "Write <value> at offset <offset> to <device>'s extcsd.\n"
> +                 "  --verify  Verify data written",
>           NULL
>         },
>         { do_writeprotect_boot_get, -1,
> diff --git a/mmc_cmds.c b/mmc_cmds.c
> index df66986..154020e 100644
> --- a/mmc_cmds.c
> +++ b/mmc_cmds.c
> @@ -1986,9 +1986,10 @@ int do_write_extcsd(int nargs, char **argv)
>         int fd, ret;
>         int offset, value;
>         char *device;
> +       int verify = 0;
> 
> -       if (nargs != 4) {
> -               fprintf(stderr, "Usage: mmc extcsd write <offset> <value>
> </path/to/mmcblkX>\n");
> +       if (nargs != 4 && nargs != 5) {
> +               fprintf(stderr, "Usage: mmc extcsd write <offset>
> + <value> </path/to/mmcblkX> [--verify]\n");
>                 exit(1);
>         }
> 
> @@ -1996,6 +1997,14 @@ int do_write_extcsd(int nargs, char **argv)
>         value  = strtol(argv[2], NULL, 0);
>         device = argv[3];
> 
> +       if (nargs == 5) {
> +               if (strcmp(argv[4], "--verify") == 0) {
> +                       verify = 1;
> +               } else {
> +                       fprintf(stderr, "Unknown argument: '%s'\n", argv[4]);
> +               }
> +       }
> +
>         fd = open(device, O_RDWR);
>         if (fd < 0) {
>                 perror("open");
> @@ -2010,6 +2019,21 @@ int do_write_extcsd(int nargs, char **argv)
>                 exit(1);
>         }
> 
> +       if (verify) {
> +               __u8 ext_csd[512];
> +
> +               ret = read_extcsd(fd, ext_csd);
> +               if (ret) {
> +                       fprintf(stderr, "Could not read EXT_CSD from %s\n", device);
> +                       exit(1);
> +               }
> +
> +               if (ext_csd[offset] != value) {
> +                       fprintf(stderr, "Verification failed: expected 0x%x, got 0x%x\n",
> value, ext_csd[offset]);
> +                       exit(1);
> +               }
> +       }
> +
>         return ret;
>  }
> 
> --
> 2.39.2