Re: [PATCH v5 7/7] ufs: core: Add error handling for MCQ mode

[Bao D. Nguyen]

On 5/21/2023 11:56 PM, Stanley Chu wrote:
> On Mon, May 22, 2023 at 2:48 PM Stanley Chu <chu.stanley@xxxxxxxxx> wrote:
> > Hi Bao,
> >
> > Bao D. Nguyen <quic_nguyenb@xxxxxxxxxxx> 於 2023年5月12日 週五 下午2:34寫道：
> > > Add support for error handling for MCQ mode.
> > >
> > > Signed-off-by: Bao D. Nguyen <quic_nguyenb@xxxxxxxxxxx>
> > > ---
> > >   drivers/ufs/core/ufshcd.c | 85 +++++++++++++++++++++++++++++++++++++++++------
> > >   1 file changed, 74 insertions(+), 11 deletions(-)
> > >
> > > diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> > > index ec07e49..9345118 100644
> > > --- a/drivers/ufs/core/ufshcd.c
> > > +++ b/drivers/ufs/core/ufshcd.c
> > > @@ -3148,6 +3148,16 @@ static int ufshcd_wait_for_dev_cmd(struct ufs_hba *hba,
> > >                  err = -ETIMEDOUT;
> > >                  dev_dbg(hba->dev, "%s: dev_cmd request timedout, tag %d\n",
> > >                          __func__, lrbp->task_tag);
> > > +
> > > +               /* MCQ mode */
> > > +               if (is_mcq_enabled(hba)) {
> > > +                       err = ufshcd_clear_cmd(hba, lrbp->task_tag);
> > > +                       if (!err)
> > > +                               hba->dev_cmd.complete = NULL;
> >
> > How about always clearing hba->dev_cmd.complete? If ufshcd_clear_cmd()
> > fails (for example, times out), "complete" should be cleared, similar
> > to the "pending" case in the SDB path.
> >
> > > +                       return err;
> > > +               }
> > > +
> > > +               /* SDB mode */
> > >                  if (ufshcd_clear_cmd(hba, lrbp->task_tag) == 0) {
> > >                          /* successfully cleared the command, retry if needed */
> > >                          err = -EAGAIN;
> > > @@ -5581,6 +5591,10 @@ static int ufshcd_poll(struct Scsi_Host *shost, unsigned int queue_num)
> > >    */
> > >   static irqreturn_t ufshcd_transfer_req_compl(struct ufs_hba *hba)
> > >   {
> > > +       struct ufshcd_lrb *lrbp;
> > > +       u32 hwq_num, utag;
> > > +       int tag;
> > > +
> > >          /* Resetting interrupt aggregation counters first and reading the
> > >           * DOOR_BELL afterward allows us to handle all the completed requests.
> > >           * In order to prevent other interrupts starvation the DB is read once
> > > @@ -5599,7 +5613,22 @@ static irqreturn_t ufshcd_transfer_req_compl(struct ufs_hba *hba)
> > >           * Ignore the ufshcd_poll() return value and return IRQ_HANDLED since we
> > >           * do not want polling to trigger spurious interrupt complaints.
> > >           */
> > > -       ufshcd_poll(hba->host, UFSHCD_POLL_FROM_INTERRUPT_CONTEXT);
> > > +       if (!is_mcq_enabled(hba)) {
> > > +               ufshcd_poll(hba->host, UFSHCD_POLL_FROM_INTERRUPT_CONTEXT);
> > > +               goto out;
> > > +       }
> > > +
> > > +       /* MCQ mode */
> > > +       for (tag = 0; tag < hba->nutrs; tag++) {
> > > +               lrbp = &hba->lrb[tag];
> > > +               if (ufshcd_cmd_inflight(lrbp->cmd)) {
> > > +                       utag = blk_mq_unique_tag(scsi_cmd_to_rq(lrbp->cmd));
> > > +                       hwq_num = blk_mq_unique_tag_to_hwq(utag);
> > > +                       ufshcd_poll(hba->host, hwq_num);
> > > +               }
> > > +       }
> >
> > In SDB mode, the DOOR_BELL is reset by ufshcd_hba_stop(). All bits
> > that were previously set in DOOR_BELL are also set in "completed_reqs"
> > in ufshcd_poll(). This allows ufshcd_poll() to handle all outstanding
> > requests properly.
> >
> > However, in MCQ mode, the CQ tail registers cannot provide the same
> > information after they are reset. Hence, they cannot be properly
> > referenced by ufshcd_poll().
>
> A fixed version sample is as follows and has been tested on our end.
Thank you Stanley. I will make the change.

> struct scsi_cmnd *cmd;
>
> for (tag = 0; tag < hba->nutrs; tag++) {
>          lrbp = &hba->lrb[tag];
>          cmd = lrbp->cmd;
>          if (ufshcd_cmd_inflight(cmd)) {
>                  set_host_byte(cmd, DID_ERROR);
>                  ufshcd_release_scsi_cmd(hba, lrbp);
>                  scsi_done(cmd);
>          }
> }
>
> Thanks,
> Stanley Chu