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

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On 14 May 2012 16:09, Subhash Jadavani <subhashj@xxxxxxxxxxxxxx> wrote:
> On 5/9/2012 8:18 PM, Saugata Das wrote:
>>
>> From: Saugata Das<saugata.das@xxxxxxxxxx>
>>
>> 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@xxxxxxxxxx>
>> ---
>>  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,
>
> can we add good name? which emulation we are disabling? It's 512B emulation
> mode, we are disabling.
>

Ok

>> +         "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 */
>
> Can we name this as EXT_CSD_USE_NATIVE_SECTOR?
>

Ok

>>
>>  /*
>>   * 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) {
>> +               ret = write_extcsd_value(fd, EXT_CSD_NATIVE_SECTOR, 1);
>
> Just curious, how are we going to power cycle the device after setting the
> USE_NATIVE_SECTOR? because DATA_SECTOR_SIZE won't be changed to 4K until we
> explicitly power cycle after setting this field.
>

I will add a "printf" instructing the user to power cycle the eMMC at
the end of the switch.

>> +
>> +               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);
>
>
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