Commit fce54ed0 authored by John Garry's avatar John Garry Committed by Martin K. Petersen
Browse files

scsi: hisi_sas: Limit max hw sectors for v3 HW 

If the controller is behind an IOMMU then the IOMMU IOVA caching range can
affect performance, as discussed in [0].

Limit the max HW sectors to not exceed this limit. We need to hardcode the
value until a proper DMA mapping API is available.

[0] https://lore.kernel.org/linux-iommu/20210129092120.1482-1-thunder.leizhen@huawei.com/

Link: https://lore.kernel.org/r/1655988119-223714-1-git-send-email-john.garry@huawei.com


Signed-off-by: default avatarJohn Garry <john.garry@huawei.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent aeaadcde

drivers/scsi/hisi_sas/hisi_sas_v3_hw.c

+7 −0
Original line number Diff line number Diff line
@@ -2782,6 +2782,7 @@ static int slave_configure_v3_hw(struct scsi_device *sdev) 
	struct hisi_hba *hisi_hba = shost_priv(shost);

	struct device *dev = hisi_hba->dev;

	int ret = sas_slave_configure(sdev);

	unsigned int max_sectors;



	if (ret)

		return ret;
@@ -2799,6 +2800,12 @@ static int slave_configure_v3_hw(struct scsi_device *sdev) 
		}

	}



	/* Set according to IOMMU IOVA caching limit */

	max_sectors = min_t(size_t, queue_max_hw_sectors(sdev->request_queue),

			    (PAGE_SIZE * 32) >> SECTOR_SHIFT);



	blk_queue_max_hw_sectors(sdev->request_queue, max_sectors);



	return 0;

}