freedreno: add helper to uncompress UBWC resource

We'll need this for a few edge cases, like image/sampler view that uses
a format that UBWC does not support with a resource originally created
in a format that UBWC does support.

NOTE we *could* in some cases do an in-place uncompress.  But that has
a couple potential sharp edges:

 1) the uncompressed buffer could have different layout, ie. a5xx
    with meta and pixel data of layers/levels interleaved.

 2) if it comes mid-batch, it would force flush, or somehow fixing
    up cmdstream for draws already emitted.  But with the resource
    shadowing approach we can rely on batch re-ordering to avoid
    splitting things.. older draws see the older compressed version,
    newer draws see the new uncompressed version of the rsc.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>

src/gallium/drivers/freedreno/freedreno_resource.c

@@ -50,6 +50,14 @@
 /* XXX this should go away, needed for 'struct winsys_handle' */
 #include "state_tracker/drm_driver.h"
 
+/* A private modifier for now, so we have a way to request tiled but not
+ * compressed.  It would perhaps be good to get real modifiers for the
+ * tiled formats, but would probably need to do some work to figure out
+ * the layout(s) of the tiled modes, and whether they are the same
+ * across generations.
+ */
+#define FD_FORMAT_MOD_QCOM_TILED	fourcc_mod_code(QCOM, 0xffffffff)
+
 /**
  * Go through the entire state and see if the resource is bound
  * anywhere. If it is, mark the relevant state as dirty. This is
@@ -304,6 +312,34 @@ fd_try_shadow_resource(struct fd_context *ctx, struct fd_resource *rsc,
 	return true;
 }
 
+/**
+ * Uncompress an UBWC compressed buffer "in place".  This works basically
+ * like resource shadowing, creating a new resource, and doing an uncompress
+ * blit, and swapping the state between shadow and original resource so it
+ * appears to the state tracker as if nothing changed.
+ */
+void
+fd_resource_uncompress(struct fd_context *ctx, struct fd_resource *rsc)
+{
+	bool success =
+		fd_try_shadow_resource(ctx, rsc, 0, NULL, FD_FORMAT_MOD_QCOM_TILED);
+
+	/* shadow should not fail in any cases where we need to uncompress: */
+	debug_assert(success);
+
+	/*
+	 * TODO what if rsc is used in other contexts, we don't currently
+	 * have a good way to rebind_resource() in other contexts.  And an
+	 * app that is reading one resource in multiple contexts, isn't
+	 * going to expect that the resource is modified.
+	 *
+	 * Hopefully the edge cases where we need to uncompress are rare
+	 * enough that they mostly only show up in deqp.
+	 */
+
+	rebind_resource(ctx, &rsc->base);
+}
+
 static struct fd_resource *
 fd_alloc_staging(struct fd_context *ctx, struct fd_resource *rsc,
 		unsigned level, const struct pipe_box *box)

src/gallium/drivers/freedreno/freedreno_resource.h

@@ -215,6 +215,7 @@ void fd_resource_context_init(struct pipe_context *pctx);
 
 uint32_t fd_setup_slices(struct fd_resource *rsc);
 void fd_resource_resize(struct pipe_resource *prsc, uint32_t sz);
+void fd_resource_uncompress(struct fd_context *ctx, struct fd_resource *rsc);
 
 bool fd_render_condition_check(struct pipe_context *pctx);