From 2c17d2da8c9ef2c5be5077d3995041791e38094d Mon Sep 17 00:00:00 2001 From: "Stephen M. Cameron" Date: Tue, 1 May 2012 11:42:30 -0500 Subject: [PATCH] [SCSI] hpsa: do not read from controller unnecessarily in completion code MSI/MSI-X interrupts can't race the DMA completion they are communicating so no need to read from controller to flush the DMA to the host if MSI or MSI-X interrupts are being used. Signed-off-by: Stephen M. Cameron Signed-off-by: James Bottomley --- drivers/scsi/hpsa.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h index 7b28d54..48f7812 100644 --- a/drivers/scsi/hpsa.h +++ b/drivers/scsi/hpsa.h @@ -258,12 +258,12 @@ static unsigned long SA5_performant_completed(struct ctlr_info *h) { unsigned long register_value = FIFO_EMPTY; - /* flush the controller write of the reply queue by reading - * outbound doorbell status register. - */ - register_value = readl(h->vaddr + SA5_OUTDB_STATUS); /* msi auto clears the interrupt pending bit. */ if (!(h->msi_vector || h->msix_vector)) { + /* flush the controller write of the reply queue by reading + * outbound doorbell status register. + */ + register_value = readl(h->vaddr + SA5_OUTDB_STATUS); writel(SA5_OUTDB_CLEAR_PERF_BIT, h->vaddr + SA5_OUTDB_CLEAR); /* Do a read in order to flush the write to the controller * (as per spec.) -- 2.7.4