power: regulator: Fix power on/off delay issue

SD initialization failure happens with some UHS-I SD cards on
iMX8MM/iMX93/iMX91 EVK after
commit 4fcba5d556b4 ("regulator: implement basic reference counter").
When sending operation condition to SD card, the OCR does not return
correct status. The root cause is regulator on/off delay is missed
in MMC power cycle with above commit, so SD card is not completely
power off.

When SD startup, the sequence of MMC power cycle is:
mmc_power_init(get vmmc_supply dev) -> mmc_power_off -> udelay(2000)
-> mmc_power_on

Before above commit, as a fixed regulator, the GPIO is set as:
  GPIO inactive (in mmc_power_init) ->
  GPIO inactive and delay off-on-delay-us (in mmc_power_off) ->
  udelay(2000) ->
  GPIO active (in mmc_power_on)

After the commit:
  GPIO inactive (in mmc_power_init) ->
  enable_count is 0, regulator_set_enable returns -EALREADY immediately,
      so GPIO is inactive but No off-on-delay-us (in mmc_power_off) ->
  udelay(2000) ->
  GPIO active (in mmc_power_on)

Move the off-on-delay-us delay before setting GPIO active to fix the issue.

Signed-off-by: Ye Li <[email protected]>
Reviewed-by: Peng Fan <[email protected]>
Signed-off-by: Peng Fan <[email protected]>

0 files changed, 0 insertions, 0 deletions