Attachment 71029 Details for Bug 54575 – Paranoia patch, #1

[patch] Paranoia patch, #1

0001-drm-i915-Perform-a-posting-read-of-the-ring-start-be.patch (text/plain), 1.25 KB, created by Chris Wilson on 2012-12-05 13:10:09 UTC

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Creator: Chris Wilson

Created: 2012-12-05 13:10:09 UTC

Size: 1.25 KB

patch

obsolete

>From 439207051dbb7cd40f6e9381c4907caa4da2e59d Mon Sep 17 00:00:00 2001
>From: Chris Wilson <chris@chris-wilson.co.uk>
>Date: Wed, 5 Dec 2012 13:05:44 +0000
>Subject: [PATCH] drm/i915: Perform a posting read of the ring start before
> enabling
>
>Mostly paranoia as the writes to the ring registers should not be
>reordered, but it should function well as an addition explicit check in
>a mysteriously fragile bit of code.
>
>References: https://bugs.freedesktop.org/show_bug.cgi?id=54575
>Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>---
> drivers/gpu/drm/i915/intel_ringbuffer.c |    3 +++
> 1 file changed, 3 insertions(+)
>
>diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
>index 53edce0..d5d5177 100644
>--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
>+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
>@@ -393,6 +393,9 @@ static int init_ring_common(struct intel_ring_buffer *ring)
> 	 * also enforces ordering), otherwise the hw might lose the new ring
> 	 * register values. */
> 	I915_WRITE_START(ring, obj->gtt_offset);
>+	if (I915_READ_START(ring) != obj->gtt_offset)
>+		DRM_ERROR("failed to set %s start to GTT offset\n", ring->name);
>+
> 	I915_WRITE_CTL(ring,
> 			((ring->size - PAGE_SIZE) & RING_NR_PAGES)
> 			| RING_VALID);
>-- 
>1.7.10.4
>

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Attachments on bug 54575: 71029 | 72249 | 72250 | 72308 | 72309 | 73267 | 73268

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