Re: [PATCH 2/7] scsi: ufs: find out sense data over scsi status values

[Sujit Reddy Thumma <sthumma@codeaurora.org>]

On 7/26/2013 7:16 PM, Seungwon Jeon wrote:
> Except for 'GOOD' and 'CHECK CONDITION', other status value
> in Response UPIU may or may contain sense data. If a non-zero
> value is in the Data Segment Length field, it means that UPIU
> has Sense Data in the Data Segment area.
>
> Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
> ---
>   drivers/scsi/ufs/ufs.h    |    1 +
>   drivers/scsi/ufs/ufshcd.c |   27 +++++++++++++++++++--------
>   2 files changed, 20 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
> index 139bc06..737c31b 100644
> --- a/drivers/scsi/ufs/ufs.h
> +++ b/drivers/scsi/ufs/ufs.h
> @@ -114,6 +114,7 @@ enum {
>   	MASK_SCSI_STATUS	= 0xFF,
>   	MASK_TASK_RESPONSE	= 0xFF00,
>   	MASK_RSP_UPIU_RESULT	= 0xFFFF,
> +	MASK_RSP_UPIU_DATA_SEG_LEN	= 0xFFFF,
>   };
>
>   /* Task management service response */
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 4cf3a2d..688ae0e 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -218,6 +218,20 @@ ufshcd_get_rsp_upiu_result(struct utp_upiu_rsp *ucd_rsp_ptr)
>   	return be32_to_cpu(ucd_rsp_ptr->header.dword_1) & MASK_RSP_UPIU_RESULT;
>   }
>
> +/*
> + * ufshcd_get_rsp_upiu_data_seg_len - Get the data segment length
> + *				from response UPIU
> + * @ucd_rsp_ptr: pointer to response UPIU
> + *
> + * Return the data segment length.
> + */
> +static inline int
> +ufshcd_get_rsp_upiu_data_seg_len(struct utp_upiu_rsp *ucd_rsp_ptr)
> +{
> +	return be32_to_cpu(ucd_rsp_ptr->header.dword_2) &
> +		MASK_RSP_UPIU_DATA_SEG_LEN;
> +}
> +
>   /**
>    * ufshcd_config_int_aggr - Configure interrupt aggregation values.
>    *		Currently there is no use case where we want to configure
> @@ -298,7 +312,8 @@ void ufshcd_send_command(struct ufs_hba *hba, unsigned int task_tag)
>   static inline void ufshcd_copy_sense_data(struct ufshcd_lrb *lrbp)
>   {
>   	int len;
> -	if (lrbp->sense_buffer) {
> +	if (lrbp->sense_buffer &&
> +	    !ufshcd_get_rsp_upiu_data_seg_len(lrbp->ucd_rsp_ptr)) {
>   		len = be16_to_cpu(lrbp->ucd_rsp_ptr->sense_data_len);
>   		memcpy(lrbp->sense_buffer,
>   			lrbp->ucd_rsp_ptr->sense_data,
> @@ -1156,21 +1171,17 @@ ufshcd_scsi_cmd_status(struct ufshcd_lrb *lrbp, int scsi_status)
>   			  SAM_STAT_CHECK_CONDITION;

The whole function is doing things wrong. It is redundant to interpret
the scsi_status at the LLD layer and make decisions while otherwise the
SCSI layer anyway knows how handle them properly.

Please see scsi_decide_disposition().

Ideally, this is what we should do -
if (response_upiu_sense_data_len > 0 && lrbp->sense_buffer) {
  ufshcd_copy_sense_data();
}
result = set_host_byte(DID_OK) |
		set_msg_byte(COMMAND_COMPLETE) |
		(scsi_status & 0xff);

>   		ufshcd_copy_sense_data(lrbp);
>   		break;
> -	case SAM_STAT_BUSY:
> -		result |= SAM_STAT_BUSY;
> -		break;
>   	case SAM_STAT_TASK_SET_FULL:
> -
>   		/*
>   		 * If a LUN reports SAM_STAT_TASK_SET_FULL, then the LUN queue
>   		 * depth needs to be adjusted to the exact number of
>   		 * outstanding commands the LUN can handle at any given time.
>   		 */
>   		ufshcd_adjust_lun_qdepth(lrbp->cmd);
> -		result |= SAM_STAT_TASK_SET_FULL;
> -		break;
> +	case SAM_STAT_BUSY:
>   	case SAM_STAT_TASK_ABORTED:
> -		result |= SAM_STAT_TASK_ABORTED;
> +		result |= scsi_status;
> +		ufshcd_copy_sense_data(lrbp);
>   		break;
>   	default:
>   		result |= DID_ERROR << 16;
>

-- 
Regards,
Sujit