Introduce _mmc_handle_undervoltage() to handle undervoltage events for
MMC/eMMC devices. This function interrupts ongoing operations using HPI
and performs a controlled suspend. After completing the sequence, the card
is marked as removed to prevent further interactions.
To support this, introduce __mmc_suspend() and __mmc_resume() as internal
helpers that omit mmc_claim_host()/mmc_release_host(), allowing them to be
called when the host is already claimed. Update mmc_shutdown() to skip the
normal shutdown sequence if the host is flagged as undervoltage to avoid
repeating of the shutdown procedure.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
drivers/mmc/core/mmc.c | 81 +++++++++++++++++++++++++++++++++++-------
1 file changed, 68 insertions(+), 13 deletions(-)
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 86b608843232..e626213e7a52 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -2104,8 +2104,8 @@ static int _mmc_flush_cache(struct mmc_host *host)
return err;
}
-static int _mmc_suspend(struct mmc_host *host, bool is_suspend,
- bool is_undervoltage)
+static int __mmc_suspend(struct mmc_host *host, bool is_suspend,
+ bool is_undervoltage)
{
unsigned int notify_type;
int err = 0;
@@ -2115,8 +2115,6 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend,
else
notify_type = EXT_CSD_POWER_OFF_LONG;
- mmc_claim_host(host);
-
if (mmc_card_suspended(host->card))
goto out;
@@ -2140,7 +2138,18 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend,
mmc_card_set_suspended(host->card);
}
out:
+ return err;
+}
+
+static int _mmc_suspend(struct mmc_host *host, bool is_suspend,
+ bool is_undervoltage)
+{
+ int err;
+
+ mmc_claim_host(host);
+ err = __mmc_suspend(host, is_suspend, is_undervoltage);
mmc_release_host(host);
+
return err;
}
@@ -2160,6 +2169,20 @@ static int mmc_suspend(struct mmc_host *host)
return err;
}
+static int __mmc_resume(struct mmc_host *host)
+{
+ int err;
+
+ if (!mmc_card_suspended(host->card))
+ return 0;
+
+ mmc_power_up(host, host->card->ocr);
+ err = mmc_init_card(host, host->card->ocr, host->card);
+ mmc_card_clr_suspended(host->card);
+
+ return err;
+}
+
/*
* This function tries to determine if the same card is still present
* and, if so, restore all state to it.
@@ -2169,16 +2192,9 @@ static int _mmc_resume(struct mmc_host *host)
int err = 0;
mmc_claim_host(host);
-
- if (!mmc_card_suspended(host->card))
- goto out;
-
- mmc_power_up(host, host->card->ocr);
- err = mmc_init_card(host, host->card->ocr, host->card);
- mmc_card_clr_suspended(host->card);
-
-out:
+ err = __mmc_resume(host);
mmc_release_host(host);
+
return err;
}
@@ -2189,6 +2205,9 @@ static int mmc_shutdown(struct mmc_host *host)
{
int err = 0;
+ if (host->undervoltage)
+ return 0;
+
/*
* In a specific case for poweroff notify, we need to resume the card
* before we can shutdown it properly.
@@ -2280,6 +2299,41 @@ static int _mmc_hw_reset(struct mmc_host *host)
return mmc_init_card(host, card->ocr, card);
}
+static int _mmc_handle_undervoltage(struct mmc_host *host)
+{
+ struct mmc_card *card = host->card;
+ int err = 0;
+
+ mmc_claim_host(host);
+
+ if (!host->card)
+ goto out;
+
+ if (mmc_can_poweroff_notify(host->card) &&
+ !(host->caps2 & MMC_CAP2_FULL_PWR_CYCLE))
+ err = __mmc_resume(host);
+
+ if (!err) {
+ err = mmc_interrupt_hpi(card);
+ if (err)
+ pr_err("%s: Interrupt HPI failed, error %d\n",
+ mmc_hostname(host), err);
+
+ err = __mmc_suspend(host, false, true);
+ }
+
+ if (err)
+ pr_err("%s: Undervoltage emergency stop failed\n",
+ mmc_hostname(host));
+
+ mmc_card_set_removed(host->card);
+
+out:
+ mmc_release_host(host);
+
+ return err;
+}
+
static const struct mmc_bus_ops mmc_ops = {
.remove = mmc_remove,
.detect = mmc_detect,
@@ -2292,6 +2346,7 @@ static const struct mmc_bus_ops mmc_ops = {
.hw_reset = _mmc_hw_reset,
.cache_enabled = _mmc_cache_enabled,
.flush_cache = _mmc_flush_cache,
+ .handle_undervoltage = _mmc_handle_undervoltage,
};
/*
--
2.39.5On 2/20/25 07:44, Oleksij Rempel wrote:
> Introduce _mmc_handle_undervoltage() to handle undervoltage events for
> MMC/eMMC devices. This function interrupts ongoing operations using HPI
> and performs a controlled suspend. After completing the sequence, the card
> is marked as removed to prevent further interactions.
>
> To support this, introduce __mmc_suspend() and __mmc_resume() as internal
> helpers that omit mmc_claim_host()/mmc_release_host(), allowing them to be
> called when the host is already claimed. Update mmc_shutdown() to skip the
> normal shutdown sequence if the host is flagged as undervoltage to avoid
> repeating of the shutdown procedure.
"of" can be removed here.
Given that this introduces large parts of the mmc handling IMO this commit
deserves a lot more explanation of what steps exactly do for which cards
and why.
>
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---
> drivers/mmc/core/mmc.c | 81 +++++++++++++++++++++++++++++++++++-------
> 1 file changed, 68 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 86b608843232..e626213e7a52 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -2104,8 +2104,8 @@ static int _mmc_flush_cache(struct mmc_host *host)
> return err;
> }
>
> -static int _mmc_suspend(struct mmc_host *host, bool is_suspend,
> - bool is_undervoltage)
> +static int __mmc_suspend(struct mmc_host *host, bool is_suspend,
> + bool is_undervoltage)
The is_undervoltage doesn't do anything? Did you forget something here?
> {
> unsigned int notify_type;
> int err = 0;
> @@ -2115,8 +2115,6 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend,
> else
> notify_type = EXT_CSD_POWER_OFF_LONG;
>
> - mmc_claim_host(host);
> -
> if (mmc_card_suspended(host->card))
> goto out;
>
> @@ -2140,7 +2138,18 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend,
> mmc_card_set_suspended(host->card);
> }
> out:
> + return err;
> +}
> +
> +static int _mmc_suspend(struct mmc_host *host, bool is_suspend,
> + bool is_undervoltage)
> +{
> + int err;
> +
> + mmc_claim_host(host);
> + err = __mmc_suspend(host, is_suspend, is_undervoltage);
> mmc_release_host(host);
> +
> return err;
> }
>
> @@ -2160,6 +2169,20 @@ static int mmc_suspend(struct mmc_host *host)
> return err;
> }
>
> +static int __mmc_resume(struct mmc_host *host)
> +{
> + int err;
> +
> + if (!mmc_card_suspended(host->card))
> + return 0;
> +
> + mmc_power_up(host, host->card->ocr);
> + err = mmc_init_card(host, host->card->ocr, host->card);
> + mmc_card_clr_suspended(host->card);
> +
> + return err;
> +}
> +
> /*
> * This function tries to determine if the same card is still present
> * and, if so, restore all state to it.
> @@ -2169,16 +2192,9 @@ static int _mmc_resume(struct mmc_host *host)
> int err = 0;
>
> mmc_claim_host(host);
> -
> - if (!mmc_card_suspended(host->card))
> - goto out;
> -
> - mmc_power_up(host, host->card->ocr);
> - err = mmc_init_card(host, host->card->ocr, host->card);
> - mmc_card_clr_suspended(host->card);
> -
> -out:
> + err = __mmc_resume(host);
> mmc_release_host(host);
> +
> return err;
> }
>
> @@ -2189,6 +2205,9 @@ static int mmc_shutdown(struct mmc_host *host)
> {
> int err = 0;
>
> + if (host->undervoltage)
> + return 0;
> +
Probably deserves a comment.
> /*
> * In a specific case for poweroff notify, we need to resume the card
> * before we can shutdown it properly.
> @@ -2280,6 +2299,41 @@ static int _mmc_hw_reset(struct mmc_host *host)
> return mmc_init_card(host, card->ocr, card);
> }
>
> +static int _mmc_handle_undervoltage(struct mmc_host *host)
> +{
> + struct mmc_card *card = host->card;
> + int err = 0;
> +
> + mmc_claim_host(host);
> +
> + if (!host->card)
> + goto out;
> +
> + if (mmc_can_poweroff_notify(host->card) &&
> + !(host->caps2 & MMC_CAP2_FULL_PWR_CYCLE))
> + err = __mmc_resume(host);
I'm not sure I follow this.
Why would we power-up a card that currently doesn't have power when we
know we are about to powerfail it?
> +
> + if (!err) {
> + err = mmc_interrupt_hpi(card);
> + if (err)
> + pr_err("%s: Interrupt HPI failed, error %d\n",
> + mmc_hostname(host), err);
There's no point in calling this for SD but I don't see why it currently
wouldn't be called for SD.
> +
> + err = __mmc_suspend(host, false, true);
> + }
> +
> + if (err)
> + pr_err("%s: Undervoltage emergency stop failed\n",
> + mmc_hostname(host));
> +
> + mmc_card_set_removed(host->card);
> +
> +out:
> + mmc_release_host(host);
> +
> + return err;
> +}
> +
> static const struct mmc_bus_ops mmc_ops = {
> .remove = mmc_remove,
> .detect = mmc_detect,
> @@ -2292,6 +2346,7 @@ static const struct mmc_bus_ops mmc_ops = {
> .hw_reset = _mmc_hw_reset,
> .cache_enabled = _mmc_cache_enabled,
> .flush_cache = _mmc_flush_cache,
> + .handle_undervoltage = _mmc_handle_undervoltage,
> };
>
> /*
On Thu, Feb 20, 2025 at 10:47:01AM +0000, Christian Loehle wrote:
> On 2/20/25 07:44, Oleksij Rempel wrote:
> > Introduce _mmc_handle_undervoltage() to handle undervoltage events for
> > MMC/eMMC devices. This function interrupts ongoing operations using HPI
> > and performs a controlled suspend. After completing the sequence, the card
> > is marked as removed to prevent further interactions.
> >
> > To support this, introduce __mmc_suspend() and __mmc_resume() as internal
> > helpers that omit mmc_claim_host()/mmc_release_host(), allowing them to be
> > called when the host is already claimed. Update mmc_shutdown() to skip the
> > normal shutdown sequence if the host is flagged as undervoltage to avoid
> > repeating of the shutdown procedure.
>
> "of" can be removed here.
>
> Given that this introduces large parts of the mmc handling IMO this commit
> deserves a lot more explanation of what steps exactly do for which cards
> and why.
ack
> >
> > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> > ---
> > drivers/mmc/core/mmc.c | 81 +++++++++++++++++++++++++++++++++++-------
> > 1 file changed, 68 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> > index 86b608843232..e626213e7a52 100644
> > --- a/drivers/mmc/core/mmc.c
> > +++ b/drivers/mmc/core/mmc.c
> > @@ -2104,8 +2104,8 @@ static int _mmc_flush_cache(struct mmc_host *host)
> > return err;
> > }
> >
> > -static int _mmc_suspend(struct mmc_host *host, bool is_suspend,
> > - bool is_undervoltage)
> > +static int __mmc_suspend(struct mmc_host *host, bool is_suspend,
> > + bool is_undervoltage)
>
> The is_undervoltage doesn't do anything? Did you forget something here?
This was done in the previous patch "mmc: core: refactor _mmc_suspend()
for undervoltage handling"
> > @@ -2189,6 +2205,9 @@ static int mmc_shutdown(struct mmc_host *host)
> > {
> > int err = 0;
> >
> > + if (host->undervoltage)
> > + return 0;
> > +
>
> Probably deserves a comment.
ack
> > /*
> > * In a specific case for poweroff notify, we need to resume the card
> > * before we can shutdown it properly.
> > @@ -2280,6 +2299,41 @@ static int _mmc_hw_reset(struct mmc_host *host)
> > return mmc_init_card(host, card->ocr, card);
> > }
> >
> > +static int _mmc_handle_undervoltage(struct mmc_host *host)
> > +{
> > + struct mmc_card *card = host->card;
> > + int err = 0;
> > +
> > + mmc_claim_host(host);
> > +
> > + if (!host->card)
> > + goto out;
> > +
> > + if (mmc_can_poweroff_notify(host->card) &&
> > + !(host->caps2 & MMC_CAP2_FULL_PWR_CYCLE))
> > + err = __mmc_resume(host);
>
> I'm not sure I follow this.
> Why would we power-up a card that currently doesn't have power when we
> know we are about to powerfail it?
It is part of the mmc_shutdown, but it is not used on my HW. So, can be
skip it.
> > +
> > + if (!err) {
> > + err = mmc_interrupt_hpi(card);
> > + if (err)
> > + pr_err("%s: Interrupt HPI failed, error %d\n",
> > + mmc_hostname(host), err);
>
> There's no point in calling this for SD but I don't see why it currently
> wouldn't be called for SD.
I tried to keep budget low, until we agree that it is the way to go.
After this patch stack is accepted, i can try to request more time to
add and test the SD handler.
--
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Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
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On 2/20/25 10:56, Oleksij Rempel wrote:
> On Thu, Feb 20, 2025 at 10:47:01AM +0000, Christian Loehle wrote:
>> On 2/20/25 07:44, Oleksij Rempel wrote:
>>> Introduce _mmc_handle_undervoltage() to handle undervoltage events for
>>> MMC/eMMC devices. This function interrupts ongoing operations using HPI
>>> and performs a controlled suspend. After completing the sequence, the card
>>> is marked as removed to prevent further interactions.
>>>
>>> To support this, introduce __mmc_suspend() and __mmc_resume() as internal
>>> helpers that omit mmc_claim_host()/mmc_release_host(), allowing them to be
>>> called when the host is already claimed. Update mmc_shutdown() to skip the
>>> normal shutdown sequence if the host is flagged as undervoltage to avoid
>>> repeating of the shutdown procedure.
>>
>> "of" can be removed here.
>>
>> Given that this introduces large parts of the mmc handling IMO this commit
>> deserves a lot more explanation of what steps exactly do for which cards
>> and why.
>
> ack
>
>>>
>>> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
>>> ---
>>> drivers/mmc/core/mmc.c | 81 +++++++++++++++++++++++++++++++++++-------
>>> 1 file changed, 68 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>>> index 86b608843232..e626213e7a52 100644
>>> --- a/drivers/mmc/core/mmc.c
>>> +++ b/drivers/mmc/core/mmc.c
>>> @@ -2104,8 +2104,8 @@ static int _mmc_flush_cache(struct mmc_host *host)
>>> return err;
>>> }
>>>
>>> -static int _mmc_suspend(struct mmc_host *host, bool is_suspend,
>>> - bool is_undervoltage)
>>> +static int __mmc_suspend(struct mmc_host *host, bool is_suspend,
>>> + bool is_undervoltage)
>>
>> The is_undervoltage doesn't do anything? Did you forget something here?
>
> This was done in the previous patch "mmc: core: refactor _mmc_suspend()
> for undervoltage handling"
Sorry!
>
>>> @@ -2189,6 +2205,9 @@ static int mmc_shutdown(struct mmc_host *host)
>>> {
>>> int err = 0;
>>>
>>> + if (host->undervoltage)
>>> + return 0;
>>> +
>>
>> Probably deserves a comment.
>
> ack
>
>>> /*
>>> * In a specific case for poweroff notify, we need to resume the card
>>> * before we can shutdown it properly.
>>> @@ -2280,6 +2299,41 @@ static int _mmc_hw_reset(struct mmc_host *host)
>>> return mmc_init_card(host, card->ocr, card);
>>> }
>>>
>>> +static int _mmc_handle_undervoltage(struct mmc_host *host)
>>> +{
>>> + struct mmc_card *card = host->card;
>>> + int err = 0;
>>> +
>>> + mmc_claim_host(host);
>>> +
>>> + if (!host->card)
>>> + goto out;
>>> +
>>> + if (mmc_can_poweroff_notify(host->card) &&
>>> + !(host->caps2 & MMC_CAP2_FULL_PWR_CYCLE))
>>> + err = __mmc_resume(host);
>>
>> I'm not sure I follow this.
>> Why would we power-up a card that currently doesn't have power when we
>> know we are about to powerfail it?
>
> It is part of the mmc_shutdown, but it is not used on my HW. So, can be
> skip it.
>
>>> +
>>> + if (!err) {
>>> + err = mmc_interrupt_hpi(card);
>>> + if (err)
>>> + pr_err("%s: Interrupt HPI failed, error %d\n",
>>> + mmc_hostname(host), err);
>>
>> There's no point in calling this for SD but I don't see why it currently
>> wouldn't be called for SD.
>
> I tried to keep budget low, until we agree that it is the way to go.
> After this patch stack is accepted, i can try to request more time to
> add and test the SD handler.
If you're not implementing this for now, why not just drop the undervoltage
event at patch 1/6 if host doesn't have an eMMC attached?
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