From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Currently we leave the cache_level of the initial fb obj set to NONE. This means on eLLC machines the first pin_to_display() will try to switch it to WT which requires a vma unbind+bind. If that happens during the fbdev initialization rcu does not seem operational which causes the unbind to get stuck. To most appearances this looks like a dead machine on boot. Avoid the unbind by already marking the object cache_level as WT when creating it. We still do an excplicit ggtt pin which will rewrite the PTEs anyway, so they will match whatever cache level we set. Cc: <stable@xxxxxxxxxxxxxxx> # v5.7+ Suggested-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2381 Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20201007120329.17076-1-ville.syrjala@xxxxxxxxxxxxxxx --- drivers/gpu/drm/i915/display/intel_display.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c index c016b5d9561e..a02ca7de72de 100644 --- a/drivers/gpu/drm/i915/display/intel_display.c +++ b/drivers/gpu/drm/i915/display/intel_display.c @@ -3449,6 +3449,14 @@ initial_plane_vma(struct drm_i915_private *i915, if (IS_ERR(obj)) return NULL; + /* + * Mark it WT ahead of time to avoid changing the + * cache_level during fbdev initialization. The + * unbind there would get stuck waiting for rcu. + */ + i915_gem_object_set_cache_coherency(obj, HAS_WT(i915) ? + I915_CACHE_WT : I915_CACHE_NONE); + switch (plane_config->tiling) { case I915_TILING_NONE: break; -- 2.20.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
