libata: remove ATA_FLAG_LOWTAG

sata_sil24 for some reason pukes when tags are allocated round-robin
which helps tag ordered controllers.  To work around the issue,
72dd299d5039 ("libata: allow sata_sil24 to opt-out of tag ordered
submission") introduced ATA_FLAG_LOWTAG which tells libata tag
allocation to do lowest-first.

However, with the recent switch to blk-mq tag allocation, the liata
tag allocation code path is no longer used and the workaround is now
implemented in the block layer and selected by setting
scsi_host_template->tag_alloc_policy to BLK_TAG_ALLOC_FIFO.  See
9269e23496dd ("libata: make sata_sil24 use fifo tag allocator").

This leaves ATA_FLAG_LOWTAG withoout any actual user.  Remove it.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Dan Williams <dan.j.williams@intel.com>

2 files changed, 2 insertions, 5 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index b061ba2c31d8..fd9be1756f0d 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -4240,10 +4240,7 @@ int ata_sas_allocate_tag(struct ata_port *ap)
         unsigned int i, tag;
 
         for (i = 0, tag = ap->sas_last_tag + 1; i < max_queue; i++, tag++) {
-                if (ap->flags & ATA_FLAG_LOWTAG)
-                        tag = 1;
-                else
-                        tag = tag < max_queue ? tag : 0;
+                tag = tag < max_queue ? tag : 0;
 
                 /* the last tag is reserved for internal command. */
                 if (tag == ATA_TAG_INTERNAL)
diff --git a/drivers/ata/sata_sil24.c b/drivers/ata/sata_sil24.c
index ba2667fa0528..52428971ba94 100644
--- a/drivers/ata/sata_sil24.c
+++ b/drivers/ata/sata_sil24.c
@@ -246,7 +246,7 @@ enum {
         /* host flags */
         SIL24_COMMON_FLAGS      = ATA_FLAG_SATA | ATA_FLAG_PIO_DMA |
                                   ATA_FLAG_NCQ | ATA_FLAG_ACPI_SATA |
-                                  ATA_FLAG_AN | ATA_FLAG_PMP | ATA_FLAG_LOWTAG,
+                                  ATA_FLAG_AN | ATA_FLAG_PMP,
         SIL24_FLAG_PCIX_IRQ_WOC = (1 << 24), /* IRQ loss errata on PCI-X */
 
         IRQ_STAT_4PORTS         = 0xf,