diff options
Diffstat (limited to 'drivers/mmc/core/mmc.c')
| -rw-r--r-- | drivers/mmc/core/mmc.c | 70 |
1 files changed, 67 insertions, 3 deletions
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index 5be9b42d5057..3e7d9437477c 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -36,6 +36,7 @@ enum mmc_poweroff_type { MMC_POWEROFF_SUSPEND, MMC_POWEROFF_SHUTDOWN, + MMC_POWEROFF_UNDERVOLTAGE, MMC_POWEROFF_UNBIND, }; @@ -2132,9 +2133,15 @@ static int _mmc_suspend(struct mmc_host *host, enum mmc_poweroff_type pm_type) if (mmc_card_suspended(host->card)) goto out; - err = _mmc_flush_cache(host); - if (err) - goto out; + /* + * For the undervoltage case, we care more about device integrity. + * Avoid cache flush and notify the device to power off quickly. + */ + if (pm_type != MMC_POWEROFF_UNDERVOLTAGE) { + err = _mmc_flush_cache(host); + if (err) + goto out; + } if (mmc_card_can_poweroff_notify(host->card) && mmc_host_can_poweroff_notify(host, pm_type)) @@ -2213,6 +2220,13 @@ static int mmc_shutdown(struct mmc_host *host) int err = 0; /* + * In case of undervoltage, the card will be powered off (removed) by + * _mmc_handle_undervoltage() + */ + if (mmc_card_removed(host->card)) + return 0; + + /* * If the card remains suspended at this point and it was done by using * the sleep-cmd (CMD5), we may need to re-initialize it first, to allow * us to send the preferred poweroff-notification cmd at shutdown. @@ -2302,6 +2316,55 @@ static int _mmc_hw_reset(struct mmc_host *host) return mmc_init_card(host, card->ocr, card); } +/** + * _mmc_handle_undervoltage - Handle an undervoltage event for MMC/eMMC devices + * @host: MMC host structure + * + * This function is triggered when an undervoltage condition is detected. + * It attempts to transition the device into a low-power or safe state to + * prevent data corruption. + * + * Steps performed: + * - Perform an emergency suspend using EXT_CSD_POWER_OFF_SHORT if possible. + * - If power-off notify is not supported, fallback mechanisms like sleep or + * deselecting the card are attempted. + * - Cache flushing is skipped to reduce execution time. + * - Mark the card as removed to prevent further interactions after + * undervoltage. + * + * Note: This function does not handle host claiming or releasing. The caller + * must ensure that the host is properly claimed before calling this + * function and released afterward. + * + * Returns: 0 on success, or a negative error code if any step fails. + */ +static int _mmc_handle_undervoltage(struct mmc_host *host) +{ + struct mmc_card *card = host->card; + int err; + + /* + * Perform an emergency suspend to power off the eMMC quickly. + * This ensures the device enters a safe state before power is lost. + * We first attempt EXT_CSD_POWER_OFF_SHORT, but if power-off notify + * is not supported, we fall back to sleep mode or deselecting the card. + * Cache flushing is skipped to minimize delay. + */ + err = _mmc_suspend(host, MMC_POWEROFF_UNDERVOLTAGE); + if (err) + pr_err("%s: undervoltage suspend failed: %pe\n", + mmc_hostname(host), ERR_PTR(err)); + + /* + * Mark the card as removed to prevent further operations. + * This ensures the system does not attempt to access the device + * after an undervoltage event, avoiding potential corruption. + */ + mmc_card_set_removed(card); + + return err; +} + static const struct mmc_bus_ops mmc_ops = { .remove = mmc_remove, .detect = mmc_detect, @@ -2314,6 +2377,7 @@ 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, }; /* |