[U-Boot] [PATCH 14/22] mmc: add power cyle support in mmc core

[Jean-Jacques Hiblot]

On 15/05/2017 05:28, Simon Glass wrote:
> Hi,
>
> On 12 May 2017 at 12:16, Jean-Jacques Hiblot <jjhiblot at ti.com> wrote:
>> mmc/sd specification requires vdd to be disabled for 1 ms
>> and then enabled again during power cycle. Add a
>> function in mmc core to perform power cycle and set
>> the io signal to it's initial state.
>>
>> Signed-off-by: Kishon Vijay Abraham I <kishon at ti.com>
>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot at ti.com>
>> ---
>>   drivers/mmc/mmc.c | 50 +++++++++++++++++++++++++++++++++++++++++---------
>>   1 file changed, 41 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
>> index d40a22b..032260b 100644
>> --- a/drivers/mmc/mmc.c
>> +++ b/drivers/mmc/mmc.c
>> @@ -30,6 +30,7 @@ static const unsigned int sd_au_size[] = {
>>          SZ_16M / 512,   (SZ_16M + SZ_8M) / 512, SZ_32M / 512,   SZ_64M / 512,
>>   };
>>   static int mmc_set_signal_voltage(struct mmc *mmc, uint signal_voltage);
>> +static void mmc_power_cycle(struct mmc *mmc);
>>
>>   #if CONFIG_IS_ENABLED(MMC_TINY)
>>   static struct mmc mmc_static;
>> @@ -1915,6 +1916,45 @@ static int mmc_power_init(struct mmc *mmc)
>>          return 0;
>>   }
>>
>> +static void mmc_set_initial_state(struct mmc *mmc)
> Function comment
OK
>
>> +{
>> +       int err;
>> +
>> +       /* First try to set 3.3V. If it fails set to 1.8V */
>> +       err = mmc_set_signal_voltage(mmc, MMC_SIGNAL_VOLTAGE_330);
>> +       if (err != 0)
>> +               err = mmc_set_signal_voltage(mmc, MMC_SIGNAL_VOLTAGE_180);
>> +       if (err != 0)
>> +               printf("failed to set signal voltage\n");
>> +
>> +       mmc_set_bus_width(mmc, 1);
>> +       mmc_set_clock(mmc, 1);
>> +       mmc_select_mode(mmc, MMC_LEGACY);
>> +}
>> +
>> +static void mmc_power_up(struct mmc *mmc)
>> +{
>> +       mmc_set_initial_state(mmc);
>> +       mmc_set_vdd(mmc, true);
>> +       udelay(10000);
> Eek. Please add a comment as to why
This is to let the Vdd time to settle. I'll remove this for the next 
version. If a delay is required by the platform it can be handled by the 
host driver.
>
>> +}
>> +
>> +static void mmc_power_off(struct mmc *mmc)
>> +{
>> +       mmc_set_vdd(mmc, false);
>> +}
>> +
>> +static void mmc_power_cycle(struct mmc *mmc)
>> +{
>> +       mmc_power_off(mmc);
>> +       /*
>> +        * SD spec recommends at least 1ms of delay. Let's wait for 2ms
>> +        * to be on the safer side.
>> +        */
>> +       udelay(2000);
>> +       mmc_power_up(mmc);
>> +}
>> +
>>   int mmc_start_init(struct mmc *mmc)
>>   {
>>          bool no_card;
>> @@ -1952,16 +1992,8 @@ int mmc_start_init(struct mmc *mmc)
>>                  return err;
>>   #endif
>>          mmc->ddr_mode = 0;
>> -       mmc_set_vdd(mmc, true);
>> -       /* First try to set 3.3V. If it fails set to 1.8V */
>> -       err = mmc_set_signal_voltage(mmc, MMC_SIGNAL_VOLTAGE_330);
>> -       if (err != 0)
>> -               err = mmc_set_signal_voltage(mmc, MMC_SIGNAL_VOLTAGE_180);
>> -       if (err != 0)
>> -               printf("failed to set signal voltage\n");
> Return error? Also please add some mmc: to your message.
>
>> -       mmc_set_bus_width(mmc, 1);
>> -       mmc_set_clock(mmc, 1);
>> +       mmc_power_cycle(mmc);
>>
>>          /* Reset the Card */
>>          err = mmc_go_idle(mmc);
>> --
>> 1.9.1
>>
> Regards,
> Simon
>