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megaraid_sas : Use writeq for 64bit pci write to avoid spinlock overhead 

Resending the patch. Addressed the review comments from Tomas Henzl.
Reduce the assingment for u64 req_data variable.

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>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Sumit.Saxena@avagotech.com 2014-09-12 18:57:18 +05:30 committed by Christoph Hellwig
parent 07e38d94ef
commit 0756040952
1 changed files with 6 additions and 0 deletions
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6
drivers/scsi/megaraid/megaraid_sas_fusion.c
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@ -1065,6 +1065,11 @@ 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 = (((u64)req_desc_hi << 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 +1077,7 @@ 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
}
/**