linux-kernel - [PATCH 3.16.y-ckt 023/180] drm/i915/vlv: remove wait for previous GFX clk disable request

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Message-Id: <1430991989-23170-24-git-send-email-luis.henriques@canonical.com>
Date:	Thu,  7 May 2015 10:43:52 +0100
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Jani Nikula <jani.nikula@...el.com>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 023/180] drm/i915/vlv: remove wait for previous GFX clk disable request

3.16.7-ckt11 -stable review patch.  If anyone has any objections, please let me know.

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

From: Jesse Barnes <jbarnes@...tuousgeek.org>

commit 5df0582bf036bb5f9a8ad8db5884fe13a55347d1 upstream.

Looks like it was introduced in:

commit 650ad970a39f8b6164fe8613edc150f585315289
Author: Imre Deak <imre.deak@...el.com>
Date:   Fri Apr 18 16:35:02 2014 +0300

    drm/i915: vlv: factor out vlv_force_gfx_clock and check for pending force-of

but I'm not sure why.  It has caused problems for us in the past (see
85250ddff7a6 "drm/i915/chv: Remove Wait for a previous gfx force-off"
and 8d4eee9cd7a1 "drm/i915: vlv: increase timeout when forcing on the
GFX clock") and doesn't seem to be required, so let's just drop it.

References: https://bugs.freedesktop.org/show_bug.cgi?id=89611
Signed-off-by: Jesse Barnes <jbarnes@...tuousgeek.org>
Tested-by: Darren Hart <dvhart@...ux.intel.com>
Reviewed-by: Deepak S <deepak.s@...ux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@...el.com>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 drivers/gpu/drm/i915/i915_drv.c | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 7a0fc58d372e..caef2e1774b3 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1175,21 +1175,7 @@ int vlv_force_gfx_clock(struct drm_i915_private *dev_priv, bool force_on)
 	u32 val;
 	int err;
 
-	val = I915_READ(VLV_GTLC_SURVIVABILITY_REG);
-
 #define COND (I915_READ(VLV_GTLC_SURVIVABILITY_REG) & VLV_GFX_CLK_STATUS_BIT)
-	/* Wait for a previous force-off to settle */
-	if (force_on && !IS_CHERRYVIEW(dev_priv->dev)) {
-		/* WARN_ON only for the Valleyview */
-		WARN_ON(!!(val & VLV_GFX_CLK_FORCE_ON_BIT) == force_on);
-
-		err = wait_for(!COND, 20);
-		if (err) {
-			DRM_ERROR("timeout waiting for GFX clock force-off (%08x)\n",
-				  I915_READ(VLV_GTLC_SURVIVABILITY_REG));
-			return err;
-		}
-	}
 
 	val = I915_READ(VLV_GTLC_SURVIVABILITY_REG);
 	val &= ~VLV_GFX_CLK_FORCE_ON_BIT;
--
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