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Commit cae6edc3 authored by Mark Lord's avatar Mark Lord Committed by Jeff Garzik
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sata_mv: don't read hc_irq_cause 



Remove silly read-modify-write sequences when clearing interrupts
in hc_irq_cause.  This gets rid of unneeded MMIO reads, resulting in
a slight performance boost when switching between EDMA and non-EDMA
modes (eg. for cache flushes).

Signed-off-by: default avatarMark Lord <mlord@pobox.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent b0bccb18

drivers/ata/sata_mv.c

+5 −12
Original line number Diff line number Diff line
@@ -35,8 +35,6 @@ 
 *

 * --> Investigate problems with PCI Message Signalled Interrupts (MSI).

 *

 * --> Cache frequently-accessed registers in mv_port_priv to reduce overhead.

 *

 * --> Develop a low-power-consumption strategy, and implement it.

 *

 * --> [Experiment, low priority] Investigate interrupt coalescing.
@@ -884,18 +882,14 @@ static void mv_start_dma(struct ata_port *ap, void __iomem *port_mmio, 
		int hardport = mv_hardport_from_port(ap->port_no);

		void __iomem *hc_mmio = mv_hc_base_from_port(

					mv_host_base(ap->host), ap->port_no);

		u32 hc_irq_cause, ipending;

		u32 hc_irq_cause;



		/* clear EDMA event indicators, if any */

		writelfl(0, port_mmio + EDMA_ERR_IRQ_CAUSE_OFS);



		/* clear EDMA interrupt indicator, if any */

		hc_irq_cause = readl(hc_mmio + HC_IRQ_CAUSE_OFS);

		ipending = (DEV_IRQ | DMA_IRQ) << hardport;

		if (hc_irq_cause & ipending) {

			writelfl(hc_irq_cause & ~ipending,

				 hc_mmio + HC_IRQ_CAUSE_OFS);

		}

		/* clear pending irq events */

		hc_irq_cause = ~((DEV_IRQ | DMA_IRQ) << hardport);

		writelfl(hc_irq_cause, hc_mmio + HC_IRQ_CAUSE_OFS);



		mv_edma_cfg(ap, want_ncq);
@@ -2821,8 +2815,7 @@ static void mv_eh_thaw(struct ata_port *ap) 
	writel(0, port_mmio + EDMA_ERR_IRQ_CAUSE_OFS);



	/* clear pending irq events */

	hc_irq_cause = readl(hc_mmio + HC_IRQ_CAUSE_OFS);

	hc_irq_cause &= ~((DEV_IRQ | DMA_IRQ) << hardport);

	hc_irq_cause = ~((DEV_IRQ | DMA_IRQ) << hardport);

	writelfl(hc_irq_cause, hc_mmio + HC_IRQ_CAUSE_OFS);



	mv_enable_port_irqs(ap, ERR_IRQ);