-----Original Message-----
From: Enrico Jorns <ejo@xxxxxxxxxxxxxx>
Sent: Monday, May 22, 2023 11:53 PM
To: linux-mmc@xxxxxxxxxxxxxxx
Cc: Avri Altman <avri.altman@xxxxxxx>; Ulf Hansson <ulf.hansson@xxxxxxxxxx>; ejo@xxxxxxxxxxxxxx
Subject: [PATCH 1/2] mmc-utils: introduce optional --verify argument for 'extcsd write'
> 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.
But it will return with an error soon, I'm working on it, anyway I think it's not a bad idea.
User needs to be aware that not all indices can be '--verify'ed, though.
>
> Signed-off-by: Enrico Jorns <ejo@xxxxxxxxxxxxxx>
> ---
> 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);
I think this error message should indicate that the write already happened.
> + 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
>
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