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@oss.qualcomm.com>
---
 drivers/ufs/core/ufs-sysfs.c | 2 +-
 include/ufs/ufshcd.h         | 2 ++
 2 files changed, 3 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)
 		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..a64c19563b03 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -834,6 +834,7 @@ enum ufshcd_mcq_opr {
  * @uic_link_state: active state of the link to the UFS device.
  * @rpm_lvl: desired UFS power management level during runtime PM.
  * @spm_lvl: desired UFS power management level during system PM.
+ * @pm_lvl_min: minimum supported power management level.
  * @pm_op_in_progress: whether or not a PM operation is in progress.
  * @ahit: value of Auto-Hibernate Idle Timer register.
  * @outstanding_tasks: Bits representing outstanding task requests
@@ -972,6 +973,7 @@ 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 */
-- 
2.34.1

On 1/13/26 12:00 AM, Ram Kumar Dwivedi wrote:
> 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.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

On Tue, Jan 13, 2026 at 01:30:45PM +0530, Ram Kumar Dwivedi wrote:
> 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@oss.qualcomm.com>

Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>

- Mani

> ---
>  drivers/ufs/core/ufs-sysfs.c | 2 +-
>  include/ufs/ufshcd.h         | 2 ++
>  2 files changed, 3 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)
>  		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..a64c19563b03 100644
> --- a/include/ufs/ufshcd.h
> +++ b/include/ufs/ufshcd.h
> @@ -834,6 +834,7 @@ enum ufshcd_mcq_opr {
>   * @uic_link_state: active state of the link to the UFS device.
>   * @rpm_lvl: desired UFS power management level during runtime PM.
>   * @spm_lvl: desired UFS power management level during system PM.
> + * @pm_lvl_min: minimum supported power management level.
>   * @pm_op_in_progress: whether or not a PM operation is in progress.
>   * @ahit: value of Auto-Hibernate Idle Timer register.
>   * @outstanding_tasks: Bits representing outstanding task requests
> @@ -972,6 +973,7 @@ 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 */
> -- 
> 2.34.1
> 

-- 
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