[PATCH i-g-t 5/6] lib/rendercopy: Always setup clear color for TGL

[Ville Syrjala <ville.syrjala@linux.intel.com>]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

TGL apparently automagically converts regular output to fast
clears when the output matches the configured clear color.
And if we don't enable the clear color packet at all then we
just get some rainbow gibberish on all black parts of the
output.

To avoid always set up the clear color packet when using
using a non-clear color modifier. We'll just stick a bunch
of NaNs into the clear value so it'll never match any
legitimate output, and thus automagic fast clear should not
happen.

TODO: Hide this better inside rendercopy_gen9.c without
      requring extra allocation in the FB BO
TODO: Figure out if other platforms need this sort stuff

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 lib/igt_fb.c          | 24 ++++++++++++++++++++++++
 lib/intel_bufops.h    |  1 +
 lib/rendercopy_gen9.c | 14 +++++++++++---
 3 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/lib/igt_fb.c b/lib/igt_fb.c
index 9d7808ba8312..857ffb6547a3 100644
--- a/lib/igt_fb.c
+++ b/lib/igt_fb.c
@@ -963,6 +963,16 @@ void igt_calc_fb_size(struct igt_fb *fb)
 		size += calc_plane_size(fb, plane);
 	}
 
+	/*
+	 * We always need a clear color on TGL, make some extra
+	 * room for one it if it's not explicit in the modifier.
+	 *
+	 * TODO: probably better to allocate this as part of the
+	 * batch instead so the fb size doesn't need to change...
+	 */
+	if (fb->modifier == I915_FORMAT_MOD_Y_TILED_GEN12_RC_CCS)
+		size = ALIGN(size + 64, 64);
+
 	if (is_xe_device(fb->fd))
 		size = ALIGN(size, xe_get_default_alignment(fb->fd));
 
@@ -2661,6 +2671,20 @@ igt_fb_create_intel_buf(int fd, struct buf_ops *bops,
 	if (fb->modifier == I915_FORMAT_MOD_4_TILED_DG2_RC_CCS_CC)
 		buf->cc.offset = fb->offsets[1];
 
+	/*
+	 * TGL appears to do automagic fast clear when rendering
+	 * black and the clear color isn't specified, or when the
+	 * output matches the specified clear color. Force a
+	 * non-sensical clear color to prevent it from doing this
+	 * when using a non-clear color modifier.
+	 *
+	 * TODO: figure out if other platforms are affected...
+	 */
+	if (fb->modifier == I915_FORMAT_MOD_Y_TILED_GEN12_RC_CCS) {
+		buf->cc.disable = true;
+		buf->cc.offset = fb->size - 64;
+	}
+
 	return buf;
 }
 
diff --git a/lib/intel_bufops.h b/lib/intel_bufops.h
index 84e71d41a2c2..06e72ba4ba93 100644
--- a/lib/intel_bufops.h
+++ b/lib/intel_bufops.h
@@ -38,6 +38,7 @@ struct intel_buf {
 	} ccs[2];
 	struct {
 		uint32_t offset;
+		bool disable;
 	} cc;
 	struct {
 		uint64_t offset;
diff --git a/lib/rendercopy_gen9.c b/lib/rendercopy_gen9.c
index 9b2d1ff688de..04ec7ec99d9a 100644
--- a/lib/rendercopy_gen9.c
+++ b/lib/rendercopy_gen9.c
@@ -1130,15 +1130,23 @@ void _gen9_render_op(struct intel_bb *ibb,
 
 	gen12_emit_aux_pgtable_state(ibb, aux_pgtable_state, true);
 
-	if (fast_clear) {
+	if (fast_clear || dst->cc.disable) {
 		for (int i = 0; i < 4; i++) {
 			intel_bb_out(ibb, MI_STORE_DWORD_IMM_GEN4);
 			intel_bb_emit_reloc(ibb, dst->handle,
 					    I915_GEM_DOMAIN_RENDER, I915_GEM_DOMAIN_RENDER,
                                             dst->cc.offset + i*sizeof(float),
 					    dst->addr.offset);
-			intel_bb_out(ibb, *(uint32_t*)&clear_color[i]);
-               }
+			if (fast_clear) {
+				intel_bb_out(ibb, *(uint32_t*)&clear_color[i]);
+			} else {
+				/*
+				 * Emit NaN so it'll match nothing and thus prevent
+				 * TGL from doing its automagic fast clear tricks.
+				 */
+				intel_bb_out(ibb, 0xffffffff);
+			}
+		}
        }
 
 
-- 
2.44.2