Alter isa interrupt behaviour on alpha. Rather than send a non-specific

EOI after the ithread runs, send the EOI when we get the interrupt and
disable the source.  After the ithread is run, the source is renabled.
Also, add isa_handle_fast_intr() which handles fast interrupts by sending
an EOI after the handler is run.

This fixes the chronic missing interrupt problems under heavy NFS load
on my UP1000 and should result in greater stability for alphas which
route all irqs through an isa pic.

Discussed with: jhb, bde (sending non-specific EOIs early was bde's idea)

1 files changed, 38 insertions, 4 deletions

diff --git a/sys/alpha/isa/isa.c b/sys/alpha/isa/isa.c
index 961860c..d22f8b0 100644
--- a/sys/alpha/isa/isa.c
+++ b/sys/alpha/isa/isa.c
@@ -282,18 +282,50 @@ struct isa_intr {
  */
 
 static void
-isa_handle_intr(void *arg)
+isa_handle_fast_intr(void *arg)
 {
 	struct isa_intr *ii = arg;
 	int irq = ii->irq;
 
 	ii->intr(ii->arg);
 
-	if (ii->irq > 7)
+	if (irq > 7)
 		outb(IO_ICU2, 0x20 | (irq & 7));
 	outb(IO_ICU1, 0x20 | (irq > 7 ? 2 : irq));
 }
 
+static void
+isa_handle_intr(void *arg)
+{
+	struct isa_intr *ii = arg;
+
+	ii->intr(ii->arg);
+}
+
+/*
+ * Send a non-specific EIO early, then disable the source
+ */
+
+static void
+isa_disable_intr(int vector)
+{
+        int irq = (vector - 0x800) >> 4;
+
+	if (irq > 7)
+		outb(IO_ICU2, 0x20 | (irq & 7));
+	outb(IO_ICU1, 0x20 | (irq > 7 ? 2 : irq));
+
+	isa_intr_disable(irq);
+}
+
+static void
+isa_enable_intr(int vector)
+{
+	int irq = (vector - 0x800) >> 4;
+	isa_intr_enable(irq);
+}
+
+
 int
 isa_setup_intr(device_t dev, device_t child,
 	       struct resource *irq, int flags,
@@ -319,10 +351,12 @@ isa_setup_intr(device_t dev, device_t child,
 
 	error = alpha_setup_intr(
 			 device_get_nameunit(child ? child : dev),
-			 0x800 + (irq->r_start << 4), isa_handle_intr, ii,
+			 0x800 + (irq->r_start << 4), 
+			 ((flags & INTR_FAST) ? isa_handle_fast_intr :
+			     isa_handle_intr), ii,
 			 ithread_priority(flags), flags, &ii->ih,
 			 &intrcnt[INTRCNT_ISA_IRQ + irq->r_start],
-			 NULL, NULL);
+			 isa_disable_intr, isa_enable_intr);
 	if (error) {
 		free(ii, M_DEVBUF);
 		return error;