From 94a335dba34ff47cad3d6d0c29b452d43a1be3c8 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Wed, 17 Jul 2013 14:51:28 +0200 Subject: [PATCH] drm/i915: correctly restore fences with objects attached MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit To avoid stalls we delay tiling changes and especially hold of committing the new fence state for as long as possible. Synchronization points are in the execbuf code and in our gtt fault handler. Unfortunately we've missed that tricky detail when adding proper fence restore code in commit 19b2dbde5732170a03bd82cc8bd442cf88d856f7 Author: Chris Wilson Date: Wed Jun 12 10:15:12 2013 +0100 drm/i915: Restore fences after resume and GPU resets The result was that we've restored fences for objects with no tiling, since the object<->fence link still existed after resume. Now that wouldn't have been too bad since any subsequent access would have fixed things up, but if we've changed from tiled to untiled real havoc happened: The tiling stride is stored -1 in the fence register, so a stride of 0 resulted in all 1s in the top 32bits, and so a completely bogus fence spanning everything from the start of the object to the top of the GTT. The tell-tale in the register dumps looks like: FENCE START 2: 0x0214d001 FENCE END 2: 0xfffff3ff Bit 11 isn't set since the hw doesn't store it, even when writing all 1s (at least on my snb here). To prevent such a gaffle in the future add a sanity check for fences with an untiled object attached in i915_gem_write_fence. v2: Fix the WARN, spotted by Chris. v3: Trying to reuse get_fences looked ugly and obfuscated the code. Instead reuse update_fence and to make it really dtrt also move the fence dirty state clearing into update_fence. Cc: Chris Wilson Cc: Stéphane Marchesin Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=60530 Cc: stable@vger.kernel.org (for 3.10 only) Reviewed-by: Chris Wilson Tested-by: Matthew Garrett Tested-by: Björn Bidar Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_gem.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 97afd2639fb6..d9e2208cfe98 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -2258,7 +2258,17 @@ void i915_gem_restore_fences(struct drm_device *dev) for (i = 0; i < dev_priv->num_fence_regs; i++) { struct drm_i915_fence_reg *reg = &dev_priv->fence_regs[i]; - i915_gem_write_fence(dev, i, reg->obj); + + /* + * Commit delayed tiling changes if we have an object still + * attached to the fence, otherwise just clear the fence. + */ + if (reg->obj) { + i915_gem_object_update_fence(reg->obj, reg, + reg->obj->tiling_mode); + } else { + i915_gem_write_fence(dev, i, NULL); + } } } @@ -2795,6 +2805,10 @@ static void i915_gem_write_fence(struct drm_device *dev, int reg, if (i915_gem_object_needs_mb(dev_priv->fence_regs[reg].obj)) mb(); + WARN(obj && (!obj->stride || !obj->tiling_mode), + "bogus fence setup with stride: 0x%x, tiling mode: %i\n", + obj->stride, obj->tiling_mode); + switch (INTEL_INFO(dev)->gen) { case 7: case 6: @@ -2836,6 +2850,7 @@ static void i915_gem_object_update_fence(struct drm_i915_gem_object *obj, fence->obj = NULL; list_del_init(&fence->lru_list); } + obj->fence_dirty = false; } static int @@ -2965,7 +2980,6 @@ i915_gem_object_get_fence(struct drm_i915_gem_object *obj) return 0; i915_gem_object_update_fence(obj, reg, enable); - obj->fence_dirty = false; return 0; } -- 2.20.1