Re: [PATCH 2/2] mmc: core: Add post-power-off-delay-ms support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The `post-power-off-delay-ms` hardware constraint is only enforced in `mmc_power_cycle()`, leaving decoupled power-off/power-on sequences vulnerable to hardware timing violations.
- [Low] Explicitly configuring a 0 ms post-power-off delay in the device tree is ignored, falling back to the 1 ms default.
--

--- Patch [2]: [PATCH 2/2] mmc: core: Add post-power-off-delay-ms support ---
commit 36ce7de56b9b7e7608c56353aede4cb3de73df5b
Author: Judith Mendez <jm@ti.com>

mmc: core: Add post-power-off-delay-ms support

This commit adds support for post-power-off-delay-ms, allowing a
configurable delay after an MMC power off.

> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 29e80e5f928e9..f9049aaf44394 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -1394,8 +1394,12 @@ void mmc_power_off(struct mmc_host *host)
>  void mmc_power_cycle(struct mmc_host *host, u32 ocr)
>  {
>  	mmc_power_off(host);
> -	/* Wait at least 1 ms according to SD spec */
> -	mmc_delay(1);
> +	if (host->post_power_off_delay_ms) {
> +		mmc_delay(host->post_power_off_delay_ms);
> +	} else {
> +		/* Wait at least 1 ms according to SD spec */
> +		mmc_delay(1);
> +	}

[Severity: Medium]
Will this delay be missed for decoupled power-off and power-on sequences?

If a device relies on post-power-off-delay-ms (e.g., 100ms) but goes through a
runtime PM suspend or system suspend, mmc_power_off() will be called, followed
later by mmc_power_up(). Because the delay is only enforced here in
mmc_power_cycle(), will the decoupled off/on path violate the power-off time
constraint?

Could mmc_power_off() record a timestamp, and mmc_power_up() calculate the
elapsed time to only delay the remaining required duration?

[Severity: Low]
Does this ignore an explicitly configured 0 ms delay?

If a developer explicitly specifies post-power-off-delay-ms = <0> in the
device tree, this condition will evaluate to false and unexpectedly fall
back to the 1 ms default.

Could this be resolved by initializing the default value in mmc_alloc_host()
and removing the if/else condition here?

>  	mmc_power_up(host, ocr);
>  }

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260716232641.2659710-1-jm@ti.com?part=2