Hi Jonas, Peng,
On 5/15/2026 10:07 PM, Peng Fan wrote:
On Mon, May 11, 2026 at 03:10:16PM +0200, Jonas Karlman wrote:
Hi again,
On 5/11/2026 10:30 AM, Jonas Karlman wrote:
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) ->
If the regulator is off at boot-on then this is working as intended.
However, if probing the regulator turns it off and that requires a
off-on-delay-us delay, maybe you are missing a regulator-boot-on
property to indicate that the regulator is on at boot/reset. That should
also align the enable count with boot-on state of the regulator.
This regulator is on at boot-on. But there is no regulator-boot-on used
in kernel upstream dts. This will require to add it specifically for u-boot.
Looking at the kernel the off-on-delay-us is applied before a regulator
is enabled, not after it is disabled like in U-Boot. Maybe U-Boot should
do something similar, in simplest form always udelay off-on-delay-us
before the regulator is enabled.
Agree, moving off-on-delay-us before regulator is enabled should work. I
will use it in v2.
Yeah. Something below should work(Not tested).
diff --git a/drivers/power/regulator/regulator_common.c
b/drivers/power/regulator/regulator_common.c
index 85af8d599ad..7bf25f6a176 100644
--- a/drivers/power/regulator/regulator_common.c
+++ b/drivers/power/regulator/regulator_common.c
@@ -68,6 +68,9 @@ int regulator_common_set_enable(const struct udevice *dev,
dev->name, enable, plat->startup_delay_us,
dm_gpio_is_valid(&plat->gpio));
+ if (enable && plat->off_on_delay_us)
+ udelay(plat->off_on_delay_us);
+
Thanks for the patch. But I think off_on_delay_us should locate just
before calling dm_gpio_set_value. Will send it in v2.
Best regards,
Ye Li
/* Enable GPIO is optional */
if (CONFIG_IS_ENABLED(DM_GPIO) && dm_gpio_is_valid(&plat->gpio)) {
/* If previously enabled, increase count */
@@ -97,9 +100,6 @@ int regulator_common_set_enable(const struct udevice *dev,
if (enable && plat->startup_delay_us)
udelay(plat->startup_delay_us);
- if (!enable && plat->off_on_delay_us)
- udelay(plat->off_on_delay_us);
-
if (enable)
plat->enable_count++;
else
Regards
Peng.
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.
Or disabled.
Does your regulator .get_enable() ops not being called or does it not
implement its own udelay() based on parsed values?
I meant set_enable() here :-)
Regards,
Jonas
Regards,
Jonas
+
return 0;
}
