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authorMark Lord <liml@rtr.ca>2009-01-19 18:05:42 -0500
committerJeff Garzik <jgarzik@redhat.com>2009-01-26 06:36:53 -0500
commitcae6edc3b5a536119374a5439d9b253cb26f05e1 (patch)
tree14c8706bb6a6a8135b12b66623e005df825b454f /drivers/ata/sata_mv.c
parentb0bccb18bc523d1d5060d25958f12438062829a9 (diff)
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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>
Diffstat (limited to 'drivers/ata/sata_mv.c')
-rw-r--r--drivers/ata/sata_mv.c17
1 files changed, 5 insertions, 12 deletions
diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index ce9d6ad..6809628 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -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);