From: Thomas Daniel Date: Fri, 9 Jan 2015 11:09:37 +0000 (+0000) Subject: drm/i915: Reset CSB read pointer in ring init X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=c0a03a2e4c4e954d9acffd3ce3521e64654c9dc8;p=deliverable%2Flinux.git drm/i915: Reset CSB read pointer in ring init A previous commit enabled execlists by default: commit 27401d126b5b ("drm/i915/bdw: Enable execlists by default where supported") This allowed routine testing of execlists which exposed a regression when resuming from suspend. The cause was tracked down the to recent changes to the ring init sequence: commit 35a57ffbb108 ("drm/i915: Only init engines once") During a suspend/resume cycle the hardware Context Status Buffer write pointer is reset. However since the recent changes to the init sequence the software CSB read pointer is no longer reset. This means that context status events are not handled correctly and new contexts are not written to the ELSP, resulting in an apparent GPU hang. Pending further changes to the ring init code, just move the ring->next_context_status_buffer initialization into gen8_init_common_ring to fix this regression. v2: Moved init into gen8_init_common_ring rather than context_enable after feedback from Daniel Vetter. Updated commit msg to reflect this and also cite commits related to the regression. Fixed bz link to correct bug. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88096 Cc: Paulo Zanoni Cc: Daniel Vetter Cc: Dave Gordon Signed-off-by: Thomas Daniel Reviewed-by: Dave Gordon Signed-off-by: Daniel Vetter --- diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index 7670a0f0f620..e405b61cdac5 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -1137,6 +1137,7 @@ static int gen8_init_common_ring(struct intel_engine_cs *ring) _MASKED_BIT_DISABLE(GFX_REPLAY_MODE) | _MASKED_BIT_ENABLE(GFX_RUN_LIST_ENABLE)); POSTING_READ(RING_MODE_GEN7(ring)); + ring->next_context_status_buffer = 0; DRM_DEBUG_DRIVER("Execlists enabled for %s\n", ring->name); memset(&ring->hangcheck, 0, sizeof(ring->hangcheck)); @@ -1394,7 +1395,6 @@ static int logical_ring_init(struct drm_device *dev, struct intel_engine_cs *rin INIT_LIST_HEAD(&ring->execlist_queue); INIT_LIST_HEAD(&ring->execlist_retired_req_list); spin_lock_init(&ring->execlist_lock); - ring->next_context_status_buffer = 0; ret = i915_cmd_parser_init_ring(ring); if (ret)