megaraid_sas: IO throttling support

This patch will add capability in driver to tell firmware that it can
throttle IOs in case controller's queue depth is downgraded post OFU
(online firmware upgrade). This feature will ensure firmware can be
downgraded from higher queue depth to lower queue depth without needing
system reboot. Added throttling code in IO path of driver, in case OS
tries to send more IOs than post OFU firmware's queue depth.

Signed-off-by: Sumit Saxena <sumit.saxena@avagotech.com>
Signed-off-by: Kashyap Desai <kashyap.desai@avagotech.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/megaraid/megaraid_sas.h b/drivers/scsi/megaraid/megaraid_sas.h
index 2a2f49134491ebcb754b99c3e7bbc9a4b5418801..c8d25a739d38b5f05c18c540487edaff15f6d852 100644 (file)
--- a/drivers/scsi/megaraid/megaraid_sas.h
+++ b/drivers/scsi/megaraid/megaraid_sas.h
@@ -1537,7 +1537,8 @@ union megasas_sgl_frame {
 typedef union _MFI_CAPABILITIES {
        struct {
 #if   defined(__BIG_ENDIAN_BITFIELD)
-               u32     reserved:21;
+               u32     reserved:20;
+               u32     support_qd_throttling:1;
                u32     support_fp_rlbypass:1;
                u32     support_vfid_in_ioframe:1;
                u32     support_ext_io_size:1;
@@ -1561,7 +1562,8 @@ typedef union _MFI_CAPABILITIES {
                u32     support_ext_io_size:1;
                u32     support_vfid_in_ioframe:1;
                u32     support_fp_rlbypass:1;
-               u32     reserved:21;
+               u32     support_qd_throttling:1;
+               u32     reserved:20;
 #endif
        } mfi_capabilities;
        __le32          reg;

diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index 6b8547cf9de4151ff535ca26fe77ffe8625b2335..2c4912f68225b45de534e5344ff60f30947ba320 100644 (file)
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -803,6 +803,7 @@ megasas_ioc_init_fusion(struct megasas_instance *instance)
        if (!dual_qdepth_disable)
                drv_ops->mfi_capabilities.support_ext_queue_depth = 1;
 
+       drv_ops->mfi_capabilities.support_qd_throttling = 1;
        /* Convert capability to LE32 */
        cpu_to_le32s((u32 *)&init_frame->driver_operations.mfi_capabilities);