- if (isl_surf_usage_is_stencil(info->usage)) {
- /* The Ivybridge PRM states that the stencil buffer's vertical alignment
- * is 8 [Ivybridge PRM, Volume 1, Part 1, Section 6.18.4.4 Alignment
- * Unit Size]. However, valign=8 is outside the set of valid values of
- * RENDER_SURFACE_STATE.SurfaceVerticalAlignment, which is VALIGN_2
- * (0x0) and VALIGN_4 (0x1).
- *
- * The PRM is generally confused about the width, height, and alignment
- * of the stencil buffer; and this confusion appears elsewhere. For
- * example, the following PRM text effectively converts the stencil
- * buffer's 8-pixel alignment to a 4-pixel alignment [Ivybridge PRM,
- * Volume 1, Part 1, Section
- * 6.18.4.2 Base Address and LOD Calculation]:
- *
- * For separate stencil buffer, the width must be mutiplied by 2 and
- * height divided by 2 as follows:
- *
- * w_L = 2*i*ceil(W_L/i)
- * h_L = 1/2*j*ceil(H_L/j)
- *
- * The root of the confusion is that, in W tiling, each pair of rows is
- * interleaved into one.
- *
- * FINISHME(chadv): Decide to set valign=4 or valign=8 after isl's API
- * is more polished.
- */