Re: [PATCH V4 3/4] scsi: ufs: core Enforce minimum pm level for sysfs configuration

[Shawn Lin]

在 2026/01/06 星期二 21:40, Ram Kumar Dwivedi 写道:
> Some UFS platforms only support a limited subset of power levels.
> Currently, the sysfs interface allows users to set any pm level
> without validating the minimum supported value. If an unsupported
> level is selected, suspend may fail.
>
> Introduce an pm_lvl_min field in the ufs_hba structure and use it
> to clamp the pm level requested via sysfs so that only supported
> levels are accepted. Platforms that require a minimum pm level
> can set this field during probe.
>
> Signed-off-by: Ram Kumar Dwivedi <ram.dwivedi@xxxxxxxxxxxxxxxx>
> ---
>   drivers/ufs/core/ufs-sysfs.c | 2 +-
>   include/ufs/ufshcd.h         | 1 +
>   2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/ufs/core/ufs-sysfs.c b/drivers/ufs/core/ufs-sysfs.c
> index b33f8656edb5..02e5468ad49d 100644
> --- a/drivers/ufs/core/ufs-sysfs.c
> +++ b/drivers/ufs/core/ufs-sysfs.c
> @@ -141,7 +141,7 @@ static inline ssize_t ufs_sysfs_pm_lvl_store(struct device *dev,
>   	if (kstrtoul(buf, 0, &value))
>   		return -EINVAL;
>   
> -	if (value >= UFS_PM_LVL_MAX)
> +	if (value >= UFS_PM_LVL_MAX || value < hba->pm_lvl_min)

It makes sense that some platform support a limited subset of power
levels. But each level is in increasing order of power savings, and you
set it to UFS_PM_LVL_5. Don't you support UFS_PM_LVL_0 the full active
mode?

>   		return -EINVAL;
>   
>   	if (ufs_pm_lvl_states[value].dev_state == UFS_DEEPSLEEP_PWR_MODE &&
> diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
> index 19154228780b..ac8697a7355b 100644
> --- a/include/ufs/ufshcd.h
> +++ b/include/ufs/ufshcd.h
> @@ -972,6 +972,7 @@ struct ufs_hba {
>   	enum ufs_pm_level rpm_lvl;
>   	/* Desired UFS power management level during system PM */
>   	enum ufs_pm_level spm_lvl;
> +	enum ufs_pm_level pm_lvl_min;
>   	int pm_op_in_progress;
>   
>   	/* Auto-Hibernate Idle Timer register value */