From: Chris Wilson Date: Thu, 18 Aug 2016 16:17:06 +0000 (+0100) Subject: drm/i915: Fallback to using unmappable memory for scanout X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=2efb813d5388e18255c54afac77bd91acd586908;p=linux-beck.git drm/i915: Fallback to using unmappable memory for scanout The existing ABI says that scanouts are pinned into the mappable region so that legacy clients (e.g. old Xorg or plymouthd) can write directly into the scanout through a GTT mapping. However if the surface does not fit into the mappable region, we are better off just trying to fit it anywhere and hoping for the best. (Any userspace that is capable of using ginormous scanouts is also likely not to rely on pure GTT updates.) With the partial vma fault support, we are no longer restricted to only using scanouts that we can pin (though it is still preferred for performance reasons and for powersaving features like FBC). v2: Skip fence pinning when not mappable. v3: Add a comment to explain the possible ramifications of not being able to use fences for unmappable scanouts. v4: Rebase to skip over some local patches v5: Rebase to defer until after we have unmappable GTT fault support Signed-off-by: Chris Wilson Cc: Deepak S Cc: Damien Lespiau Cc: Daniel Vetter Cc: Jani Nikula Reviewed-by: Joonas Lahtinen Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-27-chris@chris-wilson.co.uk --- diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index a13290a8ba30..69a994bd6afd 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3581,11 +3581,17 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj, /* As the user may map the buffer once pinned in the display plane * (e.g. libkms for the bootup splash), we have to ensure that we - * always use map_and_fenceable for all scanout buffers. + * always use map_and_fenceable for all scanout buffers. However, + * it may simply be too big to fit into mappable, in which case + * put it anyway and hope that userspace can cope (but always first + * try to preserve the existing ABI). */ - vma = i915_gem_object_ggtt_pin(obj, view, 0, alignment, - view->type == I915_GGTT_VIEW_NORMAL ? - PIN_MAPPABLE : 0); + vma = ERR_PTR(-ENOSPC); + if (view->type == I915_GGTT_VIEW_NORMAL) + vma = i915_gem_object_ggtt_pin(obj, view, 0, alignment, + PIN_MAPPABLE | PIN_NONBLOCK); + if (IS_ERR(vma)) + vma = i915_gem_object_ggtt_pin(obj, view, 0, alignment, 0); if (IS_ERR(vma)) goto err_unpin_display; diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c index 40bf2e4c804d..37415f96f906 100644 --- a/drivers/gpu/drm/i915/intel_fbc.c +++ b/drivers/gpu/drm/i915/intel_fbc.c @@ -776,6 +776,10 @@ static bool intel_fbc_can_activate(struct intel_crtc *crtc) /* The use of a CPU fence is mandatory in order to detect writes * by the CPU to the scanout and trigger updates to the FBC. + * + * Note that is possible for a tiled surface to be unmappable (and + * so have no fence associated with it) due to aperture constaints + * at the time of pinning. */ if (cache->fb.tiling_mode != I915_TILING_X || cache->fb.fence_reg == I915_FENCE_REG_NONE) {