Re: [PATCH v10 3/4] scsi: ufs: core: Make ufshcd_wl_poweroff() behave like ufshcd_wl_suspend()

[Peter Wang <peter.wang@mediatek.com>]

On Wed, 2026-11-11 at 17:18 +0900, HOYOUNG SEO wrote:
> ufshcd_wl_poweroff(), the hibernation poweroff callback, calls
> __ufshcd_wl_suspend(hba, UFS_SHUTDOWN_PM) directly and ignores the
> result. Unlike ufshcd_wl_suspend() it:
> 
>  - does not take hba->host_sem. An error handler that runs in the
>    meantime can reset the link concurrently with
> __ufshcd_wl_suspend().
>    It also leaves host_sem unbalanced: if hibernation is aborted
> after
>    ufshcd_wl_poweroff() has been called, ufshcd_wl_resume() is called
> as
>    the .restore callback and releases host_sem, which was not
> acquired;
>  - does not check pm_runtime_suspended(dev).
> __ufshcd_suspend_prepare()
>    leaves the WLUN runtime suspended if ufshcd_rpm_ok_for_spm() is
> true,
>    which is the case if rpm_lvl and spm_lvl are equal. Then
>    __ufshcd_wl_suspend() triggers error recovery and returns -EBUSY;
>  - does not set hba->is_sys_suspended, so
> ufshcd_err_handling_prepare()
>    does not restore the clocks and regulators if the .restore
> callback
>    fails;
>  - ignores errors.
> 
> Call ufshcd_wl_system_suspend() with UFS_SHUTDOWN_PM from
> ufshcd_wl_poweroff() to fix all of these, as suggested by Bart Van
> Assche. host_sem is held until ufshcd_wl_resume() releases it if
> hibernation is aborted, and released if the suspend fails. For
> UFS_SHUTDOWN_PM, __ufshcd_wl_suspend() does not convert failures into
> -EBUSY, so a positive SCSI or UIC status can be returned. A
> dev_pm_ops
> callback has to return a negative error code, so convert it.
> 
> This changes the behavior of ufshcd_wl_poweroff(): an error is now
> returned from the .poweroff callback, which aborts hibernation,
> instead
> of being ignored, and a runtime suspended WLUN is left as it is like
> in
> ufshcd_wl_suspend().
> 
> Do not use hba->shutting_down to stop the error handler: it makes
> ufs_mtk_system_suspend(), which is also the .poweroff callback of the
> MediaTek host controller, fail with -EBUSY, and nothing clears it
> when
> hibernation is aborted.
> 
> Fixes: b294ff3e3449 ("scsi: ufs: core: Enable power management for
> wlun")
> Suggested-by: Bart Van Assche <bvanassche@acm.org>
> Signed-off-by: HOYOUNG SEO <hy50.seo@samsung.com>

Reviewed-by: Peter Wang <peter.wang@mediatek.com>