[Intel-gfx] [PATCH v2 3/5] drm/i915: Overcome display engine stride limits via GTT remapping

[Chris Wilson]

Quoting Ville Syrjala (2018-09-13 21:01:38)
> +static void
> +intel_plane_remap_gtt(struct intel_plane_state *plane_state)
> +{
> +       struct drm_i915_private *dev_priv =
> +               to_i915(plane_state->base.plane->dev);
> +       struct drm_framebuffer *fb = plane_state->base.fb;
> +       struct intel_framebuffer *intel_fb = to_intel_framebuffer(fb);
> +       struct intel_rotation_info *info = &plane_state->view.rotated;
> +       unsigned int rotation = plane_state->base.rotation;
> +       int i, num_planes = fb->format->num_planes;
> +       unsigned int tile_size = intel_tile_size(dev_priv);
> +       unsigned int tile_width, tile_height;
> +       unsigned int aligned_x, aligned_y;
> +       unsigned int aligned_w, aligned_h;
> +       unsigned int src_x, src_y;
> +       unsigned int src_w, src_h;
> +       unsigned int x, y;
> +       u32 gtt_offset = 0;
> +
> +       memset(&plane_state->view, 0, sizeof(plane_state->view));
> +       plane_state->view.type = drm_rotation_90_or_270(rotation) ?
> +               I915_GGTT_VIEW_ROTATED : I915_GGTT_VIEW_REMAPPED;
> +
> +       src_x = plane_state->base.src.x1 >> 16;
> +       src_y = plane_state->base.src.y1 >> 16;
> +       src_w = drm_rect_width(&plane_state->base.src) >> 16;
> +       src_h = drm_rect_height(&plane_state->base.src) >> 16;

Just doing a quick exercise to see if we might overflow later.

src_w/src_h are 15 bits (int 31 bits >> 16). So size is 30 bits and
total size of planes[2], 31 bits. (I'm assuming we go in and out of
pages.)

Did I miss anything? Should I be asking "what about the overflow?" :)
-Chris