tree 91e4bf9e473555acbfa3a8469cb8a5ef2d89f123
parent 665e0224a3d76f36da40bd9012270fa629aa42ed
author John Garry <john.garry@huawei.com> 1602750425 +0800
committer Martin K. Petersen <martin.petersen@oracle.com> 1603748067 -0400

scsi: hisi_sas: Stop using queue #0 always for v2 hw

In commit 8d98416a55eb ("scsi: hisi_sas: Switch v3 hw to MQ"), the dispatch
function was changed to choose the delivery queue based on the request tag
HW queue index.

This heavily degrades performance for v2 hw, since the HW queues are not
exposed there, and, as such, HW queue #0 is used for every command.

Revert to previous behaviour for when nr_hw_queues is not set, that being
to choose the HW queue based on target device index.

Link: https://lore.kernel.org/r/1602750425-240341-1-git-send-email-john.garry@huawei.com
Fixes: 8d98416a55eb ("scsi: hisi_sas: Switch v3 hw to MQ")
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>