Messages in this thread | | | Subject | Re: [PATCH v2] scsi: libsas: Reset num_scatter if libata mark qc as NODATA | From | Jason Yan <> | Date | Fri, 19 Mar 2021 09:43:20 +0800 |
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在 2021/3/19 6:56, Jolly Shah 写道: > When the cache_type for the scsi device is changed, the scsi layer > issues a MODE_SELECT command. The caching mode details are communicated > via a request buffer associated with the scsi command with data > direction set as DMA_TO_DEVICE (scsi_mode_select). When this command > reaches the libata layer, as a part of generic initial setup, libata > layer sets up the scatterlist for the command using the scsi command > (ata_scsi_qc_new). This command is then translated by the libata layer > into ATA_CMD_SET_FEATURES (ata_scsi_mode_select_xlat). The libata layer > treats this as a non data command (ata_mselect_caching), since it only > needs an ata taskfile to pass the caching on/off information to the > device. It does not need the scatterlist that has been setup, so it does > not perform dma_map_sg on the scatterlist (ata_qc_issue). Unfortunately, > when this command reaches the libsas layer(sas_ata_qc_issue), libsas > layer sees it as a non data command with a scatterlist. It cannot > extract the correct dma length, since the scatterlist has not been > mapped with dma_map_sg for a DMA operation. When this partially > constructed SAS task reaches pm80xx LLDD, it results in below warning. > > "pm80xx_chip_sata_req 6058: The sg list address > start_addr=0x0000000000000000 data_len=0x0end_addr_high=0xffffffff > end_addr_low=0xffffffff has crossed 4G boundary" > > This patch updates code to handle ata non data commands separately so > num_scatter and total_xfer_len remain 0. > > Fixes: 53de092f47ff ("scsi: libsas: Set data_dir as DMA_NONE if libata marks qc as NODATA") > Signed-off-by: Jolly Shah <jollys@google.com> > --- > v2: > - reorganized code to avoid setting num_scatter twice > > drivers/scsi/libsas/sas_ata.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c > index 024e5a550759..8b9a39077dba 100644 > --- a/drivers/scsi/libsas/sas_ata.c > +++ b/drivers/scsi/libsas/sas_ata.c > @@ -201,18 +201,17 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc) > memcpy(task->ata_task.atapi_packet, qc->cdb, qc->dev->cdb_len); > task->total_xfer_len = qc->nbytes; > task->num_scatter = qc->n_elem; > + task->data_dir = qc->dma_dir; > + } else if (qc->tf.protocol == ATA_PROT_NODATA) { > + task->data_dir = DMA_NONE;
Hi Jolly & John,
We only set DMA_NONE for ATA_PROT_NODATA, I'm curious about why ATA_PROT_NCQ_NODATA and ATAPI_PROT_NODATA do not need to set DMA_NONE?
Thanks, Jason
> } else { > for_each_sg(qc->sg, sg, qc->n_elem, si) > xfer += sg_dma_len(sg); > > task->total_xfer_len = xfer; > task->num_scatter = si; > - } > - > - if (qc->tf.protocol == ATA_PROT_NODATA) > - task->data_dir = DMA_NONE; > - else > task->data_dir = qc->dma_dir; > + } > task->scatter = qc->sg; > task->ata_task.retry_count = 1; > task->task_state_flags = SAS_TASK_STATE_PENDING; >
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