sata_mv: cache main_irq_mask register in hpriv

Part five of simplifying/fixing handling of the main_irq_mask register
to resolve unexpected interrupt issues observed in 2.6.26-rc*.

Keep a cached copy of the main_irq_mask so that we don't have
to stall the CPU to read it on every pass through mv_interrupt.

This significantly speeds up interrupt handling, both for sata_mv,
and for any other driver/device sharing the same PCI IRQ line.

Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 7 insertions, 5 deletions

diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index eb7f3dafb50..2d8a7e894b7 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -458,6 +458,7 @@ struct mv_port_signal {
 
 struct mv_host_priv {
         u32                     hp_flags;
+        u32                     main_irq_mask;
         struct mv_port_signal   signal[8];
         const struct mv_hw_ops  *ops;
         int                     n_ports;
@@ -843,10 +844,12 @@ static void mv_set_main_irq_mask(struct ata_host *host,
         struct mv_host_priv *hpriv = host->private_data;
         u32 old_mask, new_mask;
 
-        old_mask = readl(hpriv->main_irq_mask_addr);
+        old_mask = hpriv->main_irq_mask;
         new_mask = (old_mask & ~disable_bits) | enable_bits;
-        if (new_mask != old_mask)
+        if (new_mask != old_mask) {
+                hpriv->main_irq_mask = new_mask;
                 writelfl(new_mask, hpriv->main_irq_mask_addr);
+        }
 }
 
 static void mv_enable_port_irqs(struct ata_port *ap,
@@ -2200,12 +2203,11 @@ static irqreturn_t mv_interrupt(int irq, void *dev_instance)
         struct ata_host *host = dev_instance;
         struct mv_host_priv *hpriv = host->private_data;
         unsigned int handled = 0;
-        u32 main_irq_cause, main_irq_mask, pending_irqs;
+        u32 main_irq_cause, pending_irqs;
 
         spin_lock(&host->lock);
         main_irq_cause = readl(hpriv->main_irq_cause_addr);
-        main_irq_mask  = readl(hpriv->main_irq_mask_addr);
-        pending_irqs   = main_irq_cause & main_irq_mask;
+        pending_irqs   = main_irq_cause & hpriv->main_irq_mask;
         /*
          * Deal with cases where we either have nothing pending, or have read
          * a bogus register value which can indicate HW removal or PCI fault.