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

[Stanley Chu <chu.stanley@gapp.nthu.edu.tw>]

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