diff options
| author | Ulf Hansson <ulf.hansson@linaro.org> | 2021-03-10 16:29:00 +0100 |
|---|---|---|
| committer | Ulf Hansson <ulf.hansson@linaro.org> | 2021-03-30 11:42:03 +0200 |
| commit | 17a17bf50612e6048a9975450cf1bd30f93815b5 (patch) | |
| tree | 4d754105cc170a9168d492ffd3db128e5f40522b /drivers/mmc/core/core.h | |
| parent | 18bbda900ffa7770b93daa1bc1ce3be39e643101 (diff) | |
mmc: core: Fix hanging on I/O during system suspend for removable cards
The mmc core uses a PM notifier to temporarily during system suspend, turn
off the card detection mechanism for removal/insertion of (e)MMC/SD/SDIO
cards. Additionally, the notifier may be used to remove an SDIO card
entirely, if a corresponding SDIO functional driver don't have the system
suspend/resume callbacks assigned. This behaviour has been around for a
very long time.
However, a recent bug report tells us there are problems with this
approach. More precisely, when receiving the PM_SUSPEND_PREPARE
notification, we may end up hanging on I/O to be completed, thus also
preventing the system from getting suspended.
In the end what happens, is that the cancel_delayed_work_sync() in
mmc_pm_notify() ends up waiting for mmc_rescan() to complete - and since
mmc_rescan() wants to claim the host, it needs to wait for the I/O to be
completed first.
Typically, this problem is triggered in Android, if there is ongoing I/O
while the user decides to suspend, resume and then suspend the system
again. This due to that after the resume, an mmc_rescan() work gets punted
to the workqueue, which job is to verify that the card remains inserted
after the system has resumed.
To fix this problem, userspace needs to become frozen to suspend the I/O,
prior to turning off the card detection mechanism. Therefore, let's drop
the PM notifiers for mmc subsystem altogether and rely on the card
detection to be turned off/on as a part of the system_freezable_wq, that we
are already using.
Moreover, to allow and SDIO card to be removed during system suspend, let's
manage this from a ->prepare() callback, assigned at the mmc_host_class
level. In this way, we can use the parent device (the mmc_host_class
device), to remove the card device that is the child, in the
device_prepare() phase.
Reported-by: Kiwoong Kim <kwmad.kim@samsung.com>
Cc: stable@vger.kernel.org # v4.5+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20210310152900.149380-1-ulf.hansson@linaro.org
Reviewed-by: Kiwoong Kim <kwmad.kim@samsung.com>
Diffstat (limited to 'drivers/mmc/core/core.h')
| -rw-r--r-- | drivers/mmc/core/core.h | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h index 575ac0257af2..8032451abaea 100644 --- a/drivers/mmc/core/core.h +++ b/drivers/mmc/core/core.h @@ -93,14 +93,6 @@ int mmc_execute_tuning(struct mmc_card *card); int mmc_hs200_to_hs400(struct mmc_card *card); int mmc_hs400_to_hs200(struct mmc_card *card); -#ifdef CONFIG_PM_SLEEP -void mmc_register_pm_notifier(struct mmc_host *host); -void mmc_unregister_pm_notifier(struct mmc_host *host); -#else -static inline void mmc_register_pm_notifier(struct mmc_host *host) { } -static inline void mmc_unregister_pm_notifier(struct mmc_host *host) { } -#endif - void mmc_wait_for_req_done(struct mmc_host *host, struct mmc_request *mrq); bool mmc_is_req_done(struct mmc_host *host, struct mmc_request *mrq); |