Re: [PATCH v12 3/6] mmc: core: Add option to keep an eMMC powered on at system suspend

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Medium] mmc: core: CQE left active in _mmc_suspend() on
  MMC_NO_POWEROFF_SUSPEND
--

commit 719eca51e9b0da2d046fb99b21cbf5ff86d8cbfe
Author: Ulf Hansson <ulf.hansson@oss.qualcomm.com>

mmc: core: Add option to keep an eMMC powered on at system suspend

This commit adds support for keeping an eMMC powered on during system
suspend when MMC_PM_KEEP_POWER is set, introducing MMC_NO_POWEROFF_SUSPEND
to skip power-off and keep the card active on resume.

> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index a02b04938e1a0..c936272bcd813 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
[ ... ]
> @@ -2157,6 +2158,15 @@ static int _mmc_suspend(struct mmc_host *host, enum mmc_poweroff_type pm_type)
>  			goto out;
>  	}
>  
> +	if (pm_type == MMC_NO_POWEROFF_SUSPEND) {
> +		if (host->retune_period) {
> +			mmc_retune_timer_stop(host);
> +			mmc_retune_needed(host);
> +		}
> +		mmc_card_set_suspended(host->card);
> +		goto out;
> +	}

[Severity: Medium]
Can this leave CQE active across suspend when _mmc_flush_cache() returns
without sending a command (for example, when the eMMC cache is disabled)?

The existing _mmc_suspend() paths turn off CQE either by issuing a legacy
command via __mmc_start_request() or by calling mmc_power_off() ->
mmc_set_initial_state().  With MMC_NO_POWEROFF_SUSPEND, if
_mmc_flush_cache() is a no-op, _mmc_suspend() returns with host->cqe_on
still true and CQHCI unhalted.  When the host driver later runs
cqhci_suspend() -> cqhci_deactivate() -> __cqhci_disable(), CQHCI_ENABLE
and host->cqe_on are cleared without calling cqhci_off() or
cq_host->ops->disable(), so later legacy commands and resume paths also
skip host->cqe_ops->cqe_off(host), leaving CQE controller state active and
breaking non-CQE commands after resume.

Should this path call host->cqe_ops->cqe_off(host) when host->cqe_on is
set?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261111194426.1652644-1-kamal.dasu@broadcom.com?part=3