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SubjectRe: [PATCH v3 4/4] scsi: hisi_sas: Add support for DIF feature for v3 hw
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John,

> +static int hisi_sas_dif_dma_map(struct hisi_hba *hisi_hba,
> + int *n_elem_dif, struct sas_task *task)
> +{
> + struct device *dev = hisi_hba->dev;
> + struct sas_ssp_task *ssp_task;
> + struct scsi_cmnd *scsi_cmnd;
> + int rc;
> +
> + if (task->num_scatter) {
> + ssp_task = &task->ssp_task;
> + scsi_cmnd = ssp_task->cmd;
> +
> + if (scsi_prot_sg_count(scsi_cmnd)) {
> + *n_elem_dif = dma_map_sg(dev,
> + scsi_prot_sglist(scsi_cmnd),
> + scsi_prot_sg_count(scsi_cmnd),
> + task->data_dir);
> +

If you're only supporting DIF there is no DMA mapping or unmapping since
the PI is generated by or verified by the HBA. No additional data is
transferred to/from host memory. The protection scatterlist will be
NULL.

> + switch (prot_op) {
> + case SCSI_PROT_READ_INSERT:
> + prot->dw0 |= T10_INSRT_EN_MSK;
> + prot->lbrtgv = lbrt_chk_val;
> + break;
> + case SCSI_PROT_READ_STRIP:
> + prot->dw0 |= (T10_RMV_EN_MSK | T10_CHK_EN_MSK);
> + prot->lbrtcv = lbrt_chk_val;
> + if (prot_type == SCSI_PROT_DIF_TYPE1)
> + prot->dw4 |= (0xc << 16);
> + else if (prot_type == SCSI_PROT_DIF_TYPE3)
> + prot->dw4 |= (0xfc << 16);
> + break;
> + case SCSI_PROT_READ_PASS:
> + prot->dw0 |= T10_CHK_EN_MSK;
> + prot->lbrtcv = lbrt_chk_val;
> + if (prot_type == SCSI_PROT_DIF_TYPE1)
> + prot->dw4 |= (0xc << 16);
> + else if (prot_type == SCSI_PROT_DIF_TYPE3)
> + prot->dw4 |= (0xfc << 16);
> + break;
> + case SCSI_PROT_WRITE_INSERT:
> + prot->dw0 |= T10_INSRT_EN_MSK;
> + prot->lbrtgv = lbrt_chk_val;
> + break;
> + case SCSI_PROT_WRITE_STRIP:
> + prot->dw0 |= (T10_RMV_EN_MSK | T10_CHK_EN_MSK);
> + prot->lbrtcv = lbrt_chk_val;
> + break;
> + case SCSI_PROT_WRITE_PASS:
> + prot->dw0 |= T10_CHK_EN_MSK;
> + prot->lbrtcv = lbrt_chk_val;
> + if (prot_type == SCSI_PROT_DIF_TYPE1)
> + prot->dw4 |= (0xc << 16);
> + else if (prot_type == SCSI_PROT_DIF_TYPE3)
> + prot->dw4 |= (0xfc << 16);
> + break;
> + default:
> + WARN(1, "prot_op(0x%x) is not valid\n", prot_op);
> + break;
> + }

DIF is WRITE_INSERT/READ_STRIP operations only.

> + if ((prot_op == SCSI_PROT_READ_INSERT) ||
> + (prot_op == SCSI_PROT_WRITE_INSERT) ||
> + (prot_op == SCSI_PROT_WRITE_PASS) ||
> + (prot_op == SCSI_PROT_READ_PASS)) {
> + unsigned int interval = scsi_prot_interval(scsi_cmnd);
> + unsigned int ilog2_interval = ilog2(interval);
> +
> + len = (task->total_xfer_len >> ilog2_interval) * 8;
> + }

if (scmd->prot_flags & SCSI_PROT_TRANSFER_PI) {

> + .sg_prot_tablesize = HISI_SAS_SGE_PAGE_CNT,

Also not required if you're only doing DIF. There is no protection
scatterlist.

Anyway. Instead of throwing the DIX stuff away, let's figure out what
the problem is.

--
Martin K. Petersen Oracle Linux Engineering

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