[PATCH 02/11] megaraid_sas : Use writeq for 64bit pci write to avoid spinlock overhead

Sumit.Saxena
2014-09-06T13:41:33Z

Use writeq() for 64bit PCI write instead of writel() to avoid additional lock overhead.

Signed-off-by: Sumit Saxena <sumit.saxena@avagotech.com>
Signed-off-by: Kashyap Desai <kashyap.desai@avagotech.com>
---
drivers/scsi/megaraid/megaraid_sas_fusion.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index 57b47fe..c69c1ac 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -1065,6 +1065,13 @@ megasas_fire_cmd_fusion(struct megasas_instance *instance,
u32 req_desc_hi,
struct megasas_register_set __iomem *regs)
{
+#if defined(writeq) && defined(CONFIG_64BIT)
+ u64 req_data = 0;
+
+ req_data = req_desc_hi;
+ req_data = ((req_data << 32) | (u32)req_desc_lo);
+ writeq(le64_to_cpu(req_data), &(regs)->inbound_low_queue_port);
+#else
unsigned long flags;

spin_lock_irqsave(&instance->hba_lock, flags);
@@ -1072,6 +1079,7 @@ megasas_fire_cmd_fusion(struct megasas_instance *instance,
writel(le32_to_cpu(req_desc_lo), &(regs)->inbound_low_queue_port);
writel(le32_to_cpu(req_desc_hi), &(regs)->inbound_high_queue_port);
spin_unlock_irqrestore(&instance->hba_lock, flags);
+#endif
}

/**
--
1.8.3.1