Megaraid_sas uses a shared pool of commands per HBA, so we
should be enabling a shared tag map.
This will allow the I/O scheduler to make better scheduling
decisions and will avoid BUSY states in the driver.

Signed-off-by: Hannes Reinecke <h...@suse.de>
---
 drivers/scsi/megaraid/megaraid_sas_base.c | 34 ++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c 
b/drivers/scsi/megaraid/megaraid_sas_base.c
index f6a69a3..996fa9a 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -1659,7 +1659,7 @@ static int megasas_slave_configure(struct scsi_device 
*sdev)
        */
        blk_queue_rq_timeout(sdev->request_queue,
                MEGASAS_DEFAULT_CMD_TIMEOUT * HZ);
-
+       sdev->tagged_supported = 1;
        return 0;
 }
 
@@ -1667,6 +1667,10 @@ static int megasas_slave_alloc(struct scsi_device *sdev)
 {
        u16             pd_index = 0;
        struct megasas_instance *instance ;
+
+       /* We have a shared tag map, so TCQ is always supported */
+       sdev->tagged_supported = 1;
+
        instance = megasas_lookup_instance(sdev->host->host_no);
        if (sdev->channel < MEGASAS_MAX_PD_CHANNELS) {
                /*
@@ -1677,13 +1681,20 @@ static int megasas_slave_alloc(struct scsi_device *sdev)
                        sdev->id;
                if (instance->pd_list[pd_index].driveState ==
                                        MR_PD_STATE_SYSTEM) {
+                       scsi_activate_tcq(sdev, MEGASAS_DEFAULT_CMD_PER_LUN);
                        return 0;
                }
                return -ENXIO;
        }
+       scsi_activate_tcq(sdev, MEGASAS_DEFAULT_CMD_PER_LUN);
        return 0;
 }
 
+static void megasas_slave_destroy(struct scsi_device *sdev)
+{
+       scsi_deactivate_tcq(sdev, 1);
+}
+
 void megaraid_sas_kill_hba(struct megasas_instance *instance)
 {
        if ((instance->pdev->device == PCI_DEVICE_ID_LSI_SAS0073SKINNY) ||
@@ -2746,6 +2757,21 @@ struct device_attribute *megaraid_host_attrs[] = {
        NULL,
 };
 
+static int megasas_change_queue_type(struct scsi_device *sdev, int tag_type)
+{
+       if (sdev->host->bqt && sdev->tagged_supported) {
+               scsi_set_tag_type(sdev, tag_type);
+
+               if (tag_type)
+                       scsi_activate_tcq(sdev, sdev->queue_depth);
+               else
+                       scsi_deactivate_tcq(sdev, sdev->queue_depth);
+       } else
+               tag_type = 0;
+
+       return tag_type;
+}
+
 /*
  * Scsi host template for megaraid_sas driver
  */
@@ -2756,6 +2782,7 @@ static struct scsi_host_template megasas_template = {
        .proc_name = "megaraid_sas",
        .slave_configure = megasas_slave_configure,
        .slave_alloc = megasas_slave_alloc,
+       .slave_destroy = megasas_slave_destroy,
        .queuecommand = megasas_queue_command,
        .eh_device_reset_handler = megasas_reset_device,
        .eh_bus_reset_handler = megasas_reset_bus_host,
@@ -2765,6 +2792,7 @@ static struct scsi_host_template megasas_template = {
        .bios_param = megasas_bios_param,
        .use_clustering = ENABLE_CLUSTERING,
        .change_queue_depth = megasas_change_queue_depth,
+       .change_queue_type = megasas_change_queue_type,
        .no_write_same = 1,
 };
 
@@ -4909,6 +4937,10 @@ static int megasas_io_attach(struct megasas_instance 
*instance)
        host->this_id = instance->init_id;
        host->sg_tablesize = instance->max_num_sge;
 
+       if (!scsi_init_shared_tag_map(host, host->can_queue))
+               printk(KERN_WARNING "megasas: enable TCQ support, depth %d",
+                       host->can_queue);
+
        if (instance->fw_support_ieee)
                instance->max_sectors_per_req = MEGASAS_MAX_SECTORS_IEEE;
 
-- 
1.8.5.2

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