linux-kernel - [ 090/135] drm/i915: only enable sdvo hotplug irq if needed

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Message-Id: <20120917003638.675589484@decadent.org.uk>
Date:	Mon, 17 Sep 2012 01:37:55 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Jani Nikula <jani.nikula@...el.com>,
	Dominik KÃ¶ppl <dominik@...work.org>,
	Daniel Vetter <daniel.vetter@...ll.ch>
Subject: [ 090/135] drm/i915: only enable sdvo hotplug irq if needed

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jani Nikula <jani.nikula@...el.com>

commit fcbc50da7753b210b4442ca9abc4efbd4e481f6e upstream.

Avoid constant wakeups caused by noisy irq lines when we don't even care
about the irq. This should be particularly useful for i945g/gm where the
hotplug has been disabled:

commit 768b107e4b3be0acf6f58e914afe4f337c00932b
Author: Daniel Vetter <daniel.vetter@...ll.ch>
Date:   Fri May 4 11:29:56 2012 +0200

    drm/i915: disable sdvo hotplug on i945g/gm

v2: While at it, remove the bogus hotplug_active read, and do not mask
hotplug_active[0] before checking whether the irq is needed, per discussion
with Daniel on IRC.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=38442
Tested-by: Dominik Köppl <dominik@...work.org>
Signed-off-by: Jani Nikula <jani.nikula@...el.com>
Signed-off-by: Daniel Vetter <daniel.vetter@...ll.ch>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/gpu/drm/i915/intel_sdvo.c |   15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -2556,7 +2556,6 @@ bool intel_sdvo_init(struct drm_device *
 		hotplug_mask = IS_SDVOB(sdvo_reg) ?
 			SDVOB_HOTPLUG_INT_STATUS_I915 : SDVOC_HOTPLUG_INT_STATUS_I915;
 	}
-	dev_priv->hotplug_supported_mask |= hotplug_mask;
 
 	drm_encoder_helper_add(&intel_encoder->base, &intel_sdvo_helper_funcs);
 
@@ -2564,14 +2563,6 @@ bool intel_sdvo_init(struct drm_device *
 	if (!intel_sdvo_get_capabilities(intel_sdvo, &intel_sdvo->caps))
 		goto err;
 
-	/* Set up hotplug command - note paranoia about contents of reply.
-	 * We assume that the hardware is in a sane state, and only touch
-	 * the bits we think we understand.
-	 */
-	intel_sdvo_get_value(intel_sdvo, SDVO_CMD_GET_ACTIVE_HOT_PLUG,
-			     &intel_sdvo->hotplug_active, 2);
-	intel_sdvo->hotplug_active[0] &= ~0x3;
-
 	if (intel_sdvo_output_setup(intel_sdvo,
 				    intel_sdvo->caps.output_flags) != true) {
 		DRM_DEBUG_KMS("SDVO output failed to setup on SDVO%c\n",
@@ -2579,6 +2570,12 @@ bool intel_sdvo_init(struct drm_device *
 		goto err;
 	}
 
+	/* Only enable the hotplug irq if we need it, to work around noisy
+	 * hotplug lines.
+	 */
+	if (intel_sdvo->hotplug_active[0])
+		dev_priv->hotplug_supported_mask |= hotplug_mask;
+
 	intel_sdvo_select_ddc_bus(dev_priv, intel_sdvo, sdvo_reg);
 
 	/* Set the input timing to the screen. Assume always input 0. */


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