libata: allow sata_sil24 to opt-out of tag ordered submission

Ronny reports: https://bugzilla.kernel.org/show_bug.cgi?id=87101
    "Since commit 8a4aeec8d "libata/ahci: accommodate tag ordered
    controllers" the access to the harddisk on the first SATA-port is
    failing on its first access. The access to the harddisk on the
    second port is working normal.

    When reverting the above commit, access to both harddisks is working
    fine again."

Maintain tag ordered submission as the default, but allow sata_sil24 to
continue with the old behavior.

Cc: <stable@vger.kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Reported-by: Ronny Hegewald <Ronny.Hegewald@online.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 23c2ae0..d1a05f9 100644 (file)
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4771,7 +4771,10 @@ static struct ata_queued_cmd *ata_qc_new(struct ata_port *ap)
                return NULL;
 
        for (i = 0, tag = ap->last_tag + 1; i < max_queue; i++, tag++) {
-               tag = tag < max_queue ? tag : 0;
+               if (ap->flags & ATA_FLAG_LOWTAG)
+                       tag = i;
+               else
+                       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 d81b20d..ea65594 100644 (file)
--- 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_AN | ATA_FLAG_PMP | ATA_FLAG_LOWTAG,
        SIL24_FLAG_PCIX_IRQ_WOC = (1 << 24), /* IRQ loss errata on PCI-X */
 
        IRQ_STAT_4PORTS         = 0xf,

diff --git a/include/linux/libata.h b/include/linux/libata.h
index f2b440e..91f705d 100644 (file)
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -231,6 +231,7 @@ enum {
        ATA_FLAG_SW_ACTIVITY    = (1 << 22), /* driver supports sw activity
                                              * led */
        ATA_FLAG_NO_DIPM        = (1 << 23), /* host not happy with DIPM */
+       ATA_FLAG_LOWTAG         = (1 << 24), /* host wants lowest available tag */
 
        /* bits 24:31 of ap->flags are reserved for LLD specific flags */