drm/i915: disable sdvo hotplug on i945g/gm
Chris Wilson dug out a hw erratum saying that there's noise on the
interrupt line on i945G chips. We also have a bug report from a i945GM
chip with an sdvo hotplug interrupt storm (and no apparent cause).
Play it safe and disable sdvo hotplug on all i945 variants.
Note that this is a regression that has been introduced in 3.1,
when we've enabled sdvo hotplug support with
commit cc68c81aed7d892deaf12d720d5455208e94cd0a
Author: Simon Farnsworth <simon.farnsworth@onelan.co.uk>
Date: Wed Sep 21 17:13:30 2011 +0100
drm/i915: Enable SDVO hotplug interrupts for HDMI and DVI
Cc: stable@kernel.org
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=38442
Reported-and-tested-by: Dominik Köppl <dominik@devwork.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index 232d77d..ae5e748 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -1220,8 +1220,14 @@
static int intel_sdvo_supports_hotplug(struct intel_sdvo *intel_sdvo)
{
+ struct drm_device *dev = intel_sdvo->base.base.dev;
u8 response[2];
+ /* HW Erratum: SDVO Hotplug is broken on all i945G chips, there's noise
+ * on the line. */
+ if (IS_I945G(dev) || IS_I945GM(dev))
+ return false;
+
return intel_sdvo_get_value(intel_sdvo, SDVO_CMD_GET_HOT_PLUG_SUPPORT,
&response, 2) && response[0];
}