[PATCH] cmd: fix do_adc_single()

[Vyacheslav Bocharov]

The source code contains an error:
- argv[2] contains <channel> arg, variable for env_set is in argv[3]
- number of args is 4

Revert 54d24d72601321f4470c4edf31c6b29adae424a7
  cmd: simplify do_adc_single()

Fixes 9de612ae4ded53f742f5f99929c06d0839471ced
  cmd: adc: Add support for storing ADC result in env variable
---
 cmd/adc.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/cmd/adc.c b/cmd/adc.c
index 195efa8661..1c5d3e10a3 100644
--- a/cmd/adc.c
+++ b/cmd/adc.c
@@ -71,6 +71,7 @@ static int do_adc_info(struct cmd_tbl *cmdtp, int flag, int 
argc,
 static int do_adc_single(struct cmd_tbl *cmdtp, int flag, int argc,
                         char *const argv[])
 {
+       char *varname = NULL;
        struct udevice *dev;
        unsigned int data;
        int ret, uV, val;
@@ -78,6 +79,9 @@ static int do_adc_single(struct cmd_tbl *cmdtp, int flag, int 
argc,
        if (argc < 3)
                return CMD_RET_USAGE;
 
+       if (argc >= 4)
+               varname = argv[3];
+
        ret = adc_channel_single_shot(argv[1], simple_strtol(argv[2], NULL, 0),
                                      &data);
        if (ret) {
@@ -95,7 +99,8 @@ static int do_adc_single(struct cmd_tbl *cmdtp, int flag, int 
argc,
                printf("%u\n", data);
        }
 
-       env_set_ulong(argv[2], val);
+       if (varname)
+               env_set_ulong(varname, val);
 
        return CMD_RET_SUCCESS;
 }
@@ -160,5 +165,5 @@ static char adc_help_text[] =
 U_BOOT_CMD_WITH_SUBCMDS(adc, "ADC sub-system", adc_help_text,
        U_BOOT_SUBCMD_MKENT(list, 1, 1, do_adc_list),
        U_BOOT_SUBCMD_MKENT(info, 2, 1, do_adc_info),
-       U_BOOT_SUBCMD_MKENT(single, 3, 1, do_adc_single),
+       U_BOOT_SUBCMD_MKENT(single, 4, 1, do_adc_single),
        U_BOOT_SUBCMD_MKENT(scan, 3, 1, do_adc_scan));
-- 
2.30.2