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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: Mark Lord <mlord@pobox.com> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
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1 changed files with 5 additions and 12 deletions
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@ -35,8 +35,6 @@
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*
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* --> Investigate problems with PCI Message Signalled Interrupts (MSI).
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*
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* --> Cache frequently-accessed registers in mv_port_priv to reduce overhead.
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*
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* --> Develop a low-power-consumption strategy, and implement it.
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*
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* --> [Experiment, low priority] Investigate interrupt coalescing.
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@ -884,18 +882,14 @@ static void mv_start_dma(struct ata_port *ap, void __iomem *port_mmio,
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int hardport = mv_hardport_from_port(ap->port_no);
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void __iomem *hc_mmio = mv_hc_base_from_port(
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mv_host_base(ap->host), ap->port_no);
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u32 hc_irq_cause, ipending;
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u32 hc_irq_cause;
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/* clear EDMA event indicators, if any */
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writelfl(0, port_mmio + EDMA_ERR_IRQ_CAUSE_OFS);
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/* clear EDMA interrupt indicator, if any */
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hc_irq_cause = readl(hc_mmio + HC_IRQ_CAUSE_OFS);
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ipending = (DEV_IRQ | DMA_IRQ) << hardport;
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if (hc_irq_cause & ipending) {
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writelfl(hc_irq_cause & ~ipending,
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hc_mmio + HC_IRQ_CAUSE_OFS);
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}
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/* clear pending irq events */
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hc_irq_cause = ~((DEV_IRQ | DMA_IRQ) << hardport);
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writelfl(hc_irq_cause, hc_mmio + HC_IRQ_CAUSE_OFS);
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mv_edma_cfg(ap, want_ncq);
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@ -2821,8 +2815,7 @@ static void mv_eh_thaw(struct ata_port *ap)
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writel(0, port_mmio + EDMA_ERR_IRQ_CAUSE_OFS);
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/* clear pending irq events */
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hc_irq_cause = readl(hc_mmio + HC_IRQ_CAUSE_OFS);
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hc_irq_cause &= ~((DEV_IRQ | DMA_IRQ) << hardport);
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hc_irq_cause = ~((DEV_IRQ | DMA_IRQ) << hardport);
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writelfl(hc_irq_cause, hc_mmio + HC_IRQ_CAUSE_OFS);
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mv_enable_port_irqs(ap, ERR_IRQ);
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