Fix very high interrupt rate for IRQ8 (rtc) unless pnpacpi=off

Workaround for broken systems with BIOS that makes RTC interrupt level
triggered and/or active low.

See http://bugzilla.kernel.org/show_bug.cgi?id=5243

Based on the patch from Shaohua Li <shaohua.li@intel.com>

Signed-off-by: Krzysztof Piotr Oledzki <ole@ans.pl>
Cc: "Li, Shaohua" <shaohua.li@intel.com>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Adam Belay <ambx1@neo.rr.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/pnp/pnpacpi/rsparser.c b/drivers/pnp/pnpacpi/rsparser.c
index 0e3b8d0ff06b..cd0a204d96d1 100644
--- a/drivers/pnp/pnpacpi/rsparser.c
+++ b/drivers/pnp/pnpacpi/rsparser.c
@@ -85,6 +85,16 @@ static void pnpacpi_parse_allocated_irqresource(struct pnp_resource_table *res,
         if (i >= PNP_MAX_IRQ)
                 return;
 
+#ifdef CONFIG_X86
+        if (gsi < 16 && (triggering != ACPI_EDGE_SENSITIVE ||
+                                polarity != ACPI_ACTIVE_HIGH)) {
+                pnp_warn("BIOS BUG: legacy PNP IRQ %d should be edge trigger, "
+                                "active high", gsi);
+                triggering = ACPI_EDGE_SENSITIVE;
+                polarity = ACPI_ACTIVE_HIGH;
+        }
+#endif
+
         res->irq_resource[i].flags = IORESOURCE_IRQ;    // Also clears _UNSET flag
         res->irq_resource[i].flags |= irq_flags(triggering, polarity);
         irq = acpi_register_gsi(gsi, triggering, polarity);