linux-kernel - [PATCH 3.2 01/27] drm/i915: Unlock panel even when LVDS is disabled

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Message-ID: <lsq.1419815491.856094403@decadent.org.uk>
Date:	Mon, 29 Dec 2014 02:11:31 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Daniel Vetter" <daniel.vetter@...ll.ch>,
	"Francois Tigeot" <ftigeot@...fpond.org>,
	"Alexey Orishko" <alexey.orishko@...il.com>,
	"Chris Wilson" <chris@...is-wilson.co.uk>,
	"Jani Nikula" <jani.nikula@...el.com>,
	"Daniel Vetter" <daniel.vetter@...el.com>
Subject: [PATCH 3.2 01/27] drm/i915: Unlock panel even when LVDS is disabled

3.2.66-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Daniel Vetter <daniel.vetter@...ll.ch>

commit b0616c5306b342ceca07044dbc4f917d95c4f825 upstream.

Otherwise we'll have backtraces in assert_panel_unlocked because the
BIOS locks the register. In the reporter's case this regression was
introduced in

commit c31407a3672aaebb4acddf90944a114fa5c8af7b
Author: Chris Wilson <chris@...is-wilson.co.uk>
Date:   Thu Oct 18 21:07:01 2012 +0100

    drm/i915: Add no-lvds quirk for Supermicro X7SPA-H

Reported-by: Alexey Orishko <alexey.orishko@...il.com>
Cc: Alexey Orishko <alexey.orishko@...il.com>
Cc: Chris Wilson <chris@...is-wilson.co.uk>
Cc: Francois Tigeot <ftigeot@...fpond.org>
Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
Tested-by: Alexey Orishko <alexey.orishko@...il.com>
Signed-off-by: Jani Nikula <jani.nikula@...el.com>
[bwh: Backported to 3.2: adjust context; comment was duplicated]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -914,6 +914,18 @@ bool intel_lvds_init(struct drm_device *
 	int pipe;
 	u8 pin;
 
+	/*
+	 * Unlock registers and just leave them unlocked. Do this before
+	 * checking quirk lists to avoid bogus WARNINGs.
+	 */
+	if (HAS_PCH_SPLIT(dev)) {
+		I915_WRITE(PCH_PP_CONTROL,
+			   I915_READ(PCH_PP_CONTROL) | PANEL_UNLOCK_REGS);
+	} else {
+		I915_WRITE(PP_CONTROL,
+			   I915_READ(PP_CONTROL) | PANEL_UNLOCK_REGS);
+	}
+
 	/* Skip init on machines we know falsely report LVDS */
 	if (dmi_check_system(intel_no_lvds))
 		return false;
@@ -1088,19 +1100,6 @@ out:
 		pwm = I915_READ(BLC_PWM_PCH_CTL1);
 		pwm |= PWM_PCH_ENABLE;
 		I915_WRITE(BLC_PWM_PCH_CTL1, pwm);
-		/*
-		 * Unlock registers and just
-		 * leave them unlocked
-		 */
-		I915_WRITE(PCH_PP_CONTROL,
-			   I915_READ(PCH_PP_CONTROL) | PANEL_UNLOCK_REGS);
-	} else {
-		/*
-		 * Unlock registers and just
-		 * leave them unlocked
-		 */
-		I915_WRITE(PP_CONTROL,
-			   I915_READ(PP_CONTROL) | PANEL_UNLOCK_REGS);
 	}
 	dev_priv->lid_notifier.notifier_call = intel_lid_notify;
 	if (acpi_lid_notifier_register(&dev_priv->lid_notifier)) {

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