[U-Boot] [PATCH] cmd_mmc.c: check mmc_init() during mmc dev

[Stephen Warren <swarren@wwwdotorg.org>]

On 05/19/2014 06:17 PM, Bryan Wu wrote:
> mmc dev ${devnum} will return 0 as success even if there is no card
> inserted. Booting script like tegra-common-post.h will call mmc dev
> ${devnum} to check the mmc device status, it always return 0 even if
> mmc_init() fails.
> 
> Check mmc_init() return value let mmc dev command return failure
> when mmc_init() fails.

You probably want to Cc the MMC maintainer.

> diff --git a/common/cmd_mmc.c b/common/cmd_mmc.c

> @@ -195,6 +195,7 @@ static int do_mmcops(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
>  	} else if (strcmp(argv[1], "dev") == 0) {
>  		int dev, part = -1;
>  		struct mmc *mmc;
> +		int ret;

The latest u-boot.git master branch already declares ret a couple lines
above. Hence, this patch doesn't compile.

> -		mmc_init(mmc);
> +		ret = mmc_init(mmc);
> +		if (ret)
> +			return ret;

I know that I said off-list to return ret here, but it actually looks
like U-Boot commands must not return arbitrary values, but rather must
return 0, 1, or CMD_RET_USAGE. The current code prints the following on
failure:

Tegra124 (Jetson TK1) # mmc dev 1
MMC: no card present
exit not allowed from main input shell.

I'll send a V2 patch with these fixed.