From 5eaf391c59cd20adc68ea0c6db3d5f72c7aa75a3 Mon Sep 17 00:00:00 2001 From: Chris Wilson 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 --- 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