Re: [RFC 2/2] [MMC-4.5] [MMC UTIL] Disable emulation

[Subhash Jadavani <subhashj@codeaurora.org>]

On 5/9/2012 8:18 PM, Saugata Das wrote:
> From: Saugata Das<saugata.das@linaro.org>
>
> In this patch, we add utility to disable emulation mode in the eMMC-4.5.
> This is done to increase the data sector size to 4KB.
>
> Signed-off-by: Saugata Das<saugata.das@linaro.org>
> ---
>   mmc.c      |    6 ++++++
>   mmc.h      |    2 ++
>   mmc_cmds.c |   42 ++++++++++++++++++++++++++++++++++++++++++
>   mmc_cmds.h |    1 +
>   4 files changed, 51 insertions(+), 0 deletions(-)
>
> diff --git a/mmc.c b/mmc.c
> index c27fc24..43b95aa 100644
> --- a/mmc.c
> +++ b/mmc.c
> @@ -65,6 +65,12 @@ static struct Command commands[] = {
>   		"Set the eMMC writeprotect status of<device>.",
>   	  NULL
>   	},
> +	{ do_disable_emulation, -1,
> +	  "disable emulation", "<device>\n"
> +		"Set the eMMC data sector size to 4KB by disabling emulation<device>.",
> +	  NULL
> +	},
> +
>   	{ 0, 0, 0, 0 }
>   };
>
> diff --git a/mmc.h b/mmc.h
> index 3af36f1..a2050fa 100644
> --- a/mmc.h
> +++ b/mmc.h
> @@ -35,6 +35,8 @@
>   #define EXT_CSD_PART_SWITCH_TIME	199
>   #define EXT_CSD_BOOT_CFG		179
>   #define EXT_CSD_BOOT_WP			173
> +#define EXT_CSD_NATIVE_SECTOR_SIZE	63 /* R */
> +#define EXT_CSD_NATIVE_SECTOR	62 /* R/W */
>
>   /*
>    * EXT_CSD field definitions
> diff --git a/mmc_cmds.c b/mmc_cmds.c
> index 4562cef..2713ccd 100644
> --- a/mmc_cmds.c
> +++ b/mmc_cmds.c
> @@ -168,6 +168,48 @@ int do_writeprotect_set(int nargs, char **argv)
>   	return ret;
>   }
>
> +
> +int do_disable_emulation(int nargs, char **argv)
> +{
> +	__u8 ext_csd[512], native_sector_size;
> +	int fd, ret;
> +	char *device;
> +
> +	CHECK(nargs != 2, "Usage: mmc</path/to/mmcblkX>\n", exit(1));
> +
> +	device = argv[1];
> +
> +	fd = open(device, O_RDWR);
> +	if (fd<  0) {
> +		perror("open");
> +		exit(1);
> +	}
> +
> +	ret = read_extcsd(fd, ext_csd);
> +	if (ret) {
> +		fprintf(stderr, "Could not read EXT_CSD from %s\n", device);
> +		exit(1);
> +	}
> +
> +	native_sector_size = ext_csd[EXT_CSD_NATIVE_SECTOR_SIZE];
> +
> +	if (native_sector_size) {
Before setting the use_native_sector field, can you also check if 
NATIVE_SECTOR_SIZE and DATA_SECTOR_SIZE fields are different. If they 
are same then there is no need to set the USE_NATIVE_SECTOR size field.

> +		ret = write_extcsd_value(fd, EXT_CSD_NATIVE_SECTOR, 1);
> +
> +		if (ret) {
> +			fprintf(stderr, "Could not write 0x%02x to "
> +				"EXT_CSD[%d] in %s\n",
> +				1, EXT_CSD_BOOT_WP, device);
> +			exit(1);
> +		}
> +	} else {
> +		printf("MMC does not support 4KB native sector\n");
> +	}
> +
> +	return ret;
> +}
> +
> +
>   int do_read_extcsd(int nargs, char **argv)
>   {
>   	__u8 ext_csd[512], ext_csd_rev, reg;
> diff --git a/mmc_cmds.h b/mmc_cmds.h
> index 66e9acb..dd107d5 100644
> --- a/mmc_cmds.h
> +++ b/mmc_cmds.h
> @@ -19,3 +19,4 @@ int do_read_extcsd(int nargs, char **argv);
>   int do_write_extcsd(int nargs, char **argv);
>   int do_writeprotect_get(int nargs, char **argv);
>   int do_writeprotect_set(int nargs, char **argv);
> +int do_disable_emulation(int nargs, char **argv);