Hi,
On 5/11/2026 9:49 AM, Ye Li wrote:
> 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)
>
> Add the on/off delay and startup delay after GPIO request in
> regulator_common_of_to_plat which is called in regulator device probing.
> So in mmc_power_init, after GPIO is set to default inactive, the
> off-on-delay-us is applied.
>
> Signed-off-by: Ye Li <[email protected]>
> ---
> drivers/power/regulator/regulator_common.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/power/regulator/regulator_common.c
> b/drivers/power/regulator/regulator_common.c
> index 85af8d599ad..158284a3309 100644
> --- a/drivers/power/regulator/regulator_common.c
> +++ b/drivers/power/regulator/regulator_common.c
> @@ -46,6 +46,12 @@ int regulator_common_of_to_plat(struct udevice *dev,
> dev_read_u32_default(dev, "u-boot,off-on-delay-us", 0);
> }
>
> + if ((flags & GPIOD_IS_OUT_ACTIVE) && plat->startup_delay_us)
> + udelay(plat->startup_delay_us);
> +
> + if (!(flags & GPIOD_IS_OUT_ACTIVE) && plat->off_on_delay_us)
> + udelay(plat->off_on_delay_us);
regulator_common_of_to_plat() is for parsing the values, no udelay()
should be applied here.
regulator_common_set_enable() applies udelay() when the regulator is
enabled.
Does your regulator .get_enable() ops not being called or does it not
implement its own udelay() based on parsed values?
Regards,
Jonas
> +
> return 0;
> }
>
