RE: [PATCH v1] ufs: core: complete wl runtime resume after SCSI EH

["Fang Hongjie(方洪杰)" <hongjiefang@asrmicro.com>]

> From: Bart Van Assche [mailto:bvanassche@acm.org]
> Sent: Wednesday, May 27, 2026 4:47 AM
> To: Fang Hongjie(方洪杰) <hongjiefang@asrmicro.com>;
> alim.akhtar@samsung.com; avri.altman@wdc.com;
> James.Bottomley@HansenPartnership.com; martin.petersen@oracle.com;
> peter.wang@mediatek.com; beanhuo@micron.com
> Cc: linux-scsi@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v1] ufs: core: complete wl runtime resume after SCSI EH
> 
> On 5/26/26 4:49 AM, Hongjie Fang wrote:
> > diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> > index c3f08957d179..e7517cf23f06 100644
> > --- a/drivers/ufs/core/ufshcd.c
> > +++ b/drivers/ufs/core/ufshcd.c
> > @@ -10368,6 +10368,22 @@ static int __ufshcd_wl_suspend(struct
> ufs_hba *hba, enum ufs_pm_op pm_op)
> >   }
> >
> >   #ifdef CONFIG_PM
> > +static int ufshcd_wl_resume_pm_recovered(struct ufs_hba *hba)
> > +{
> > +	int ret = 0;
> > +	struct scsi_device *sdp = hba->ufs_device_wlun;
> > +
> > +	if (!sdp || !scsi_block_when_processing_errors(sdp))
> > +		return 0;
> > +
> > +	if (hba->ufshcd_state == UFSHCD_STATE_OPERATIONAL &&
> > +	    ufshcd_is_link_active(hba) &&
> > +	    ufshcd_is_ufs_dev_active(hba))
> > +		ret = 1;
> > +
> > +	return ret;
> > +}
> > +
> >   static int __ufshcd_wl_resume(struct ufs_hba *hba, enum ufs_pm_op
> pm_op)
> >   {
> >   	int ret;
> > @@ -10422,6 +10438,9 @@ static int __ufshcd_wl_resume(struct ufs_hba
> *hba, enum ufs_pm_op pm_op)
> >
> >   	if (!ufshcd_is_ufs_dev_active(hba)) {
> >   		ret = ufshcd_set_dev_pwr_mode(hba,
> UFS_ACTIVE_PWR_MODE);
> > +		if (pm_op == UFS_RUNTIME_PM && ret == -EIO &&
> > +		    ufshcd_wl_resume_pm_recovered(hba))
> > +			ret = 0;
> >   		if (ret)
> >   			goto set_old_link_state;
> >   		ufshcd_set_timestamp_attr(hba);
> 
> This change increases the complexity of the UFS driver too much. Please
> consider building a solution for this issue on top of the (untested)
> patch below. The patch below prevents that the SCSI EH is activated if a
> START STOP UNIT command times out:
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 9e0336098e26..4be5453efb34 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -9491,7 +9491,7 @@ static enum scsi_timeout_action
> ufshcd_eh_timed_out(struct scsi_cmnd *scmd)
>   {
>   	struct ufs_hba *hba = shost_priv(scmd->device->host);
> 
> -	if (!hba->system_suspending) {
> +	if (!hba->pm_op_in_progress) {
>   		/* Activate the error handler in the SCSI core. */
>   		return SCSI_EH_NOT_HANDLED;
>   	}

Thanks for the suggestion. I agree that preventing the PM START STOP UNIT
timeout from entering the regular SCSI EH path is cleaner than handling
the race after scsi_execute_cmd() returns.

I looked closer at the direct ufshcd_link_recovery() approach from
ufshcd_eh_timed_out(). There is one detail that I think needs to be
handled.

For the legacy single-doorbell path, force_compl=true currently
still calls ufshcd_transfer_req_compl(), which only completes requests for
which the doorbell bit has already been cleared:
  completed_reqs = ~tr_doorbell & hba->outstanding_reqs;

So if the timed-out SSU is still marked in both hba->outstanding_reqs and
the transfer request doorbell after ufshcd_hba_stop(), it will not be
completed by ufshcd_complete_requests(hba, true). Returning
SCSI_EH_RESET_TIMER in that state would only restart the request timer and
would not wake the blk_execute_rq() waiter.



> @@ -10543,7 +10543,6 @@ static int ufshcd_wl_suspend(struct device *dev)
> 
>   	hba = shost_priv(sdev->host);
>   	down(&hba->host_sem);
> -	hba->system_suspending = true;
> 
>   	if (pm_runtime_suspended(dev))
>   		goto out;
> @@ -10585,7 +10584,6 @@ static int ufshcd_wl_resume(struct device *dev)
>   		hba->curr_dev_pwr_mode, hba->uic_link_state);
>   	if (!ret)
>   		hba->is_sys_suspended = false;
> -	hba->system_suspending = false;
>   	up(&hba->host_sem);
>   	return ret;
>   }
> diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
> index 3eaae082329c..248d0a5bef40 100644
> --- a/include/ufs/ufshcd.h
> +++ b/include/ufs/ufshcd.h
> @@ -1029,8 +1029,6 @@ enum ufshcd_mcq_opr {
>    * @caps: bitmask with information about UFS controller capabilities
>    * @devfreq: frequency scaling information owned by the devfreq core
>    * @clk_scaling: frequency scaling information owned by the UFS driver
> - * @system_suspending: system suspend has been started and system
> resume has
> - *	not yet finished.
>    * @is_sys_suspended: UFS device has been suspended because of system
> suspend
>    * @urgent_bkops_lvl: keeps track of urgent bkops level for device
>    * @is_urgent_bkops_lvl_checked: keeps track if the urgent bkops level for
> @@ -1206,7 +1204,6 @@ struct ufs_hba {
> 
>   	struct devfreq *devfreq;
>   	struct ufs_clk_scaling clk_scaling;
> -	bool system_suspending;
>   	bool is_sys_suspended;
> 
>   	enum bkops_status urgent_bkops_lvl;
> 
> Thanks,
> 
> Bart.


Best.