Re: [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 <jjhib...@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 <kis...@ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhib...@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


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