Attachment 62980 Details for Bug 50243 – Implement w/a for sporadic read failures

[patch] Implement w/a for sporadic read failures

0001-drm-i915-Implement-w-a-for-sporadic-read-failures-on.patch (text/plain), 2.71 KB, created by Chris Wilson on 2012-06-13 10:35:51 UTC

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Creator: Chris Wilson

Created: 2012-06-13 10:35:51 UTC

Size: 2.71 KB

patch

obsolete

>From 9a9c35923d971d201fad088dd154406a38214db5 Mon Sep 17 00:00:00 2001
>From: Chris Wilson <chris@chris-wilson.co.uk>
>Date: Wed, 13 Jun 2012 18:25:22 +0100
>Subject: [PATCH] drm/i915: Implement w/a for sporadic read failures on waking
> from rc6
>
>As a w/a to prevent reads sporadically returning 0, we need to wait for
>the GT thread to return to TC0 before proceeding to read the registers.
>
>References: https://bugs.freedesktop.org/show_bug.cgi?id=50243
>Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>---
> drivers/gpu/drm/i915/i915_drv.c |   19 +++++++++++++++++++
> drivers/gpu/drm/i915/i915_reg.h |    3 +++
> 2 files changed, 22 insertions(+)
>
>diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
>index 2058316..ba3f1a9 100644
>--- a/drivers/gpu/drm/i915/i915_drv.c
>+++ b/drivers/gpu/drm/i915/i915_drv.c
>@@ -424,6 +424,19 @@ bool i915_semaphore_is_enabled(struct drm_device *dev)
> 	return 1;
> }
> 
>+static void __gen6_gt_wait_for_thread_c0(struct drm_i915_private *dev_priv)
>+{
>+	unsigned long timeout;
>+
>+	/* w/a for a sporadic read returning 0 by waiting for the GT
>+	 * thread to wake up.
>+	 */
>+	timeout = jiffies + msecs_to_jiffies(1);
>+	while (I915_READ_NOTRACE(GEN6_GT_THREAD_STATUS_REG) & GEN6_GT_THREAD_STATUS_CORE_MASK &&
>+	       time_before(jiffies, timeout))
>+		;
>+}
>+
> static void __gen6_gt_force_wake_get(struct drm_i915_private *dev_priv)
> {
> 	unsigned long timeout;
>@@ -439,6 +452,8 @@ static void __gen6_gt_force_wake_get(struct drm_i915_private *dev_priv)
> 	while ((I915_READ_NOTRACE(FORCEWAKE_ACK) & 1) == 0 &&
> 	       time_before(jiffies, timeout))
> 		;
>+
>+	__gen6_gt_wait_for_thread_c0(dev_priv);
> }
> 
> static void __gen6_gt_force_wake_mt_get(struct drm_i915_private *dev_priv)
>@@ -456,6 +471,8 @@ static void __gen6_gt_force_wake_mt_get(struct drm_i915_private *dev_priv)
> 	while ((I915_READ_NOTRACE(FORCEWAKE_MT_ACK) & 1) == 0 &&
> 	       time_before(jiffies, timeout))
> 		;
>+
>+	__gen6_gt_wait_for_thread_c0(dev_priv);
> }
> 
> /*
>@@ -546,6 +563,8 @@ static void vlv_force_wake_get(struct drm_i915_private *dev_priv)
> 	count = 0;
> 	while (count++ < 50 && (I915_READ_NOTRACE(FORCEWAKE_ACK_VLV) & 1) == 0)
> 		udelay(10);
>+
>+	__gen6_gt_wait_for_thread_c0(dev_priv);
> }
> 
> static void vlv_force_wake_put(struct drm_i915_private *dev_priv)
>diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
>index 23f8954..b51414e 100644
>--- a/drivers/gpu/drm/i915/i915_reg.h
>+++ b/drivers/gpu/drm/i915/i915_reg.h
>@@ -1443,6 +1443,9 @@
> #define DDRMPLL1		0X12c20
> #define PEG_BAND_GAP_DATA	0x14d68
> 
>+#define GEN6_GT_THREAD_STATUS_REG 0x13805c
>+#define GEN6_GT_THREAD_STATUS_CORE_MASK 0x7
>+
> #define GEN6_GT_PERF_STATUS	0x145948
> #define GEN6_RP_STATE_LIMITS	0x145994
> #define GEN6_RP_STATE_CAP	0x145998
>-- 
>1.7.10
>

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