From: Sean Paul <seanpaul@xxxxxxxxxxxx> commit f01db988ef6f6c70a6cc36ee71e4a98a68901229 upstream I have seen a number of "blt ring initialization failed" messages where the ctl or start registers are not the correct value. Upon further inspection, if the code just waited a little bit, it would read the correct value. Adding the wait_for to these reads should eliminate the issue. Signed-off-by: Sean Paul <seanpaul@xxxxxxxxxxxx> Reviewed-by: Ben Widawsky <ben@xxxxxxxxxxxx> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx> Signed-off-by: Egbert Eich <eich@xxxxxxx> [bwh: Backported to 3.0: adjust context] --- This upstream commit is required (together with 3eef8918ff440837f6af791942d8dd07e1a268ee) to fix the issue described in https://bugs.freedesktop.org/show_bug.cgi?id=54575 which on some Intel Gen4 chipsets occurs intermittently or even permanently. These two commits are part of the stable 3.2 and 3.4 branch but are missing from the 3.0 branch. This patch has been adjusted slightly to apply to that branch. drivers/gpu/drm/i915/intel_ringbuffer.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index 3bd85f7..38ae0ec 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -185,9 +185,9 @@ static int init_ring_common(struct intel_ring_buffer *ring) | RING_REPORT_64K | RING_VALID); /* If the head is still not zero, the ring is dead */ - if ((I915_READ_CTL(ring) & RING_VALID) == 0 || - I915_READ_START(ring) != obj->gtt_offset || - (I915_READ_HEAD(ring) & HEAD_ADDR) != 0) { + if (wait_for((I915_READ_CTL(ring) & RING_VALID) != 0 && + I915_READ_START(ring) == obj->gtt_offset && + (I915_READ_HEAD(ring) & HEAD_ADDR) == 0, 50)) { DRM_ERROR("%s initialization failed " "ctl %08x head %08x tail %08x start %08x\n", ring->name, -- 1.7.6.1 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html