Attachment 56463 Details for Bug 45492 – No more HEAD please, I'm British!

[patch] No more HEAD please, I'm British!

0001-drm-i915-Remove-use-of-the-autoreported-ringbuffer-H.patch (text/plain), 2.08 KB, created by Chris Wilson on 2012-02-01 10:46:23 UTC

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Creator: Chris Wilson

Created: 2012-02-01 10:46:23 UTC

Size: 2.08 KB

patch

obsolete

>From 5eaf391c59cd20adc68ea0c6db3d5f72c7aa75a3 Mon Sep 17 00:00:00 2001
>From: Chris Wilson <chris@chris-wilson.co.uk>
>Date: Wed, 1 Feb 2012 18:25:28 +0000
>Subject: [PATCH] drm/i915: Remove use of the autoreported ringbuffer HEAD
> position
>
>This was originally introduced to workaround reads of the ringbuffer
>registers returning 0 on SandyBridge causing hangs due to ringbuffer
>overflow. The root cause here was reads through the GT powerwell require
>the forcewake dance, something we only learnt of later. Now it appears
>that reading the reported head position from the HWS is returning
>garbage, leading once again to hangs.
>
>In addition, the automatic reporting of the head position is scheduled
>to be defeatured in the future. It has no more utility, remove it.
>
>Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=45492
>Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>---
> drivers/gpu/drm/i915/intel_ringbuffer.c |   14 +-------------
> 1 files changed, 1 insertions(+), 13 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
>index 023739f..620b2ed 100644
>--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
>+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
>@@ -287,7 +287,7 @@ static int init_ring_common(struct intel_ring_buffer *ring)
> 
> 	I915_WRITE_CTL(ring,
> 			((ring->size - PAGE_SIZE) & RING_NR_PAGES)
>-			| RING_REPORT_64K | RING_VALID);
>+			| RING_VALID);
> 
> 	/* If the head is still not zero, the ring is dead */
> 	if ((I915_READ_CTL(ring) & RING_VALID) == 0 ||
>@@ -1059,18 +1059,6 @@ int intel_wait_ring_buffer(struct intel_ring_buffer *ring, int n)
> 	struct drm_device *dev = ring->dev;
> 	struct drm_i915_private *dev_priv = dev->dev_private;
> 	unsigned long end;
>-	u32 head;
>-
>-	/* If the reported head position has wrapped or hasn't advanced,
>-	 * fallback to the slow and accurate path.
>-	 */
>-	head = intel_read_status_page(ring, 4);
>-	if (head > ring->head) {
>-		ring->head = head;
>-		ring->space = ring_space(ring);
>-		if (ring->space >= n)
>-			return 0;
>-	}
> 
> 	trace_i915_ring_wait_begin(ring);
> 	if (drm_core_check_feature(dev, DRIVER_GEM))
>-- 
>1.7.8.3
>

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Attachments on bug 45492: 56439 | 56445 | 56453 | 56463 | 56479 | 56480 | 56481 | 56522 | 56749 | 56750 | 56765

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