RE: [RFC PATCH v1 1/2] ufs: introduce callbacks to get command information

["Kiwoong Kim" <kwmad.kim@samsung.com>]

> Hi Kiwoong,
> 
> Kiwoong Kim <kwmad.kim@samsung.com> 於 2020年6月20日 週六 下午3:00寫道：
> >
> > Some SoC specific might need command history for various reasons, such
> > as stacking command contexts in system memory to check for debugging
> > in the future or scaling some DVFS knobs to boost IO throughput.
> >
> > What you would do with the information could be variant per SoC
> > vendor.
> >
> > Signed-off-by: Kiwoong Kim <kwmad.kim@samsung.com>
> > ---
> >  drivers/scsi/ufs/ufshcd.c | 4 ++++
> >  drivers/scsi/ufs/ufshcd.h | 8 ++++++++
> >  2 files changed, 12 insertions(+)
> >
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index 52abe82..0eae3ce 100644
> > --- a/drivers/scsi/ufs/ufshcd.c
> > +++ b/drivers/scsi/ufs/ufshcd.c
> > @@ -2545,6 +2545,8 @@ static int ufshcd_queuecommand(struct Scsi_Host
> *host, struct scsi_cmnd *cmd)
> >         /* issue command to the controller */
> >         spin_lock_irqsave(hba->host->host_lock, flags);
> >         ufshcd_vops_setup_xfer_req(hba, tag, true);
> > +       if (cmd)
> > +               ufshcd_vops_cmd_log(hba, cmd, 1);
> >         ufshcd_send_command(hba, tag);
> >  out_unlock:
> >         spin_unlock_irqrestore(hba->host->host_lock, flags); @@
> > -4890,6 +4892,8 @@ static void __ufshcd_transfer_req_compl(struct
> ufs_hba *hba,
> >                         /* Mark completed command as NULL in LRB */
> >                         lrbp->cmd = NULL;
> >                         lrbp->compl_time_stamp = ktime_get();
> > +                       ufshcd_vops_cmd_log(hba, cmd, 2);
> > +
> >                         /* Do not touch lrbp after scsi done */
> >                         cmd->scsi_done(cmd);
> >                         __ufshcd_release(hba);
> 
> If your cmd_log vop callbacks are only existed in "ufshcd_queuecommand"
> and "ufshcd_transfer_req_compl", perhaps you could re-use
> "ufshcd_vops_setup_xfer_req()" and an added "ufshcd_vops_compl_req()"
> instead of a brand new "ufshcd_vops_cmd_log()" ?
> 
> Thanks,
> Stanley Chu

Currently, ufshcd_vops_setup_xfer_req doesn't get scsi_cmnd variable.
Actually, when introduced this callback first, I was willing to make it do that
but someone gave me another idea. Then do you agree to change argument set of the function?

And I can't find ufshcd_vops_compl_req in 5.9/scsi-queue. Could you let me know where to find?

Thank you for your opinions.