<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Fri, Jun 2, 2017 at 12:57 PM, Nanley Chery <<a href="mailto:nanleychery@gmail.com" target="_blank">nanleychery@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Fri, May 26, 2017 at 04:30:18PM -0700, Jason Ekstrand wrote: > This enum describes all of the states that a auxiliary compressed ^ an <div><div class="h5">> surface can have. All of the states as well as normative language for > referring to each of the compression operations is provided in the > truly colossal comment for the new isl_aux_state enum. There is also > a diagram showing how surfaces move between the different states. > --- > src/intel/isl/isl.h | 142 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 142 insertions(+) > > diff --git a/src/intel/isl/isl.h b/src/intel/isl/isl.h > index b9d8fa8..df6d3e3 100644 > --- a/src/intel/isl/isl.h > +++ b/src/intel/isl/isl.h > @@ -560,6 +560,148 @@ enum isl_aux_usage { > ISL_AUX_USAGE_CCS_E, > }; > > +/** > + * Enum for keeping track of the state an auxiliary compressed surface. > + * > + * For any given auxiliary surface compression format (HiZ, CCS, or MCS), any > + * given slice (lod + array layer) can be in one of the six states described > + * by this enum. Draw and resolve operations may cause the slice to change > + * from one state to another. The six valid states are: > + * > + * 1) Clear: In this state, each block in the auxiliary surface contains a > + * magic value that indicates that the block is in the clear state. If > + * a block is in the clear state, it's values in the primary surface are > + * ignored and the color of the samples in the block is taken either the > + * RENDER_SURFACE_STATE packet for color or 3DSTATE_CLEAR_PARAMS for > + * depth. Since neither the primary surface nor the auxiliary surface > + * contains the clear value, the surface can be cleared to a different > + * color by simply changing the clear color without modifying either > + * surface. > + * > + * 2) Compressed w/ Clear: In this state, neither the auxiliary surface > + * nor the primary surface has a complete representation of the data. > + * Instead, both surfaces must be used together or else rendering > + * corruption may occur. Depending on the auxiliary compression format > + * and the data, any given block in the primary surface may contain all, > + * some, or none of the data required to reconstruct the actual sample > + * values. Blocks may also be in the clear state (see Clear) and have > + * their value taken from outside the surface. > + * > + * 3) Compressed w/o Clear: This state is identical to the state above > + * except that no blocks are in the clear state. In this state, all of > + * the data required to reconstruct the final sample values is contained > + * in the auxiliary and primary surface and the clear value is not > + * considered. > + * > + * 4) Resolved: In this state, the primary surface contains 100% of the > + * data. The auxiliary surface is also valid so the surface can be > + * validly used with or without aux enabled. The auxiliary surface may, > + * however, contain non-trivial data and any update to the primary > + * surface with aux disabled will cause the two to get out of sync. > + * > + * 5) Pass-through: In this state, the primary surface contains 100% of the > + * data and every block in the auxiliary surface contains a magic value > + * which indicates that the auxiliary surface should be ignored and the > + * only the primary surface should be considered. Updating the primary > + * surface without aux works fine and can be done repeatedly in this > + * mode. Writing to a surface in pass-through mode with aux enabled may > + * cause the auxiliary buffer to contain non-trivial data and no longer > + * be in the pass-through state. > + * > + * 5) Aux Invalid: In this state, the primary surface contains 100% of the </div></div> ^ 6 > + * data and the auxiliary surface is completely bogus. Any attempt to > + * use the auxiliary surface is liable to result in rendering > + * corruption. The only thing that one can do to re-enable aux once > + * this state is reached is to use an ambiguate pass to transition into > + * the pass-through state. > + * > + * Drawing with or without aux enabled may implicitly cause the surface to > + * transition between these states. There are also four types of "resolve" > + * operations which cause an explicit transition: > + * I'm not sure why Fast Clear is described as a "resolve" operation. To me, "resolve" operations are those which make data in one buffer match the data in another buffer. Perhaps you can clarify this? <div><div class="h5"></div></div></blockquote><div> </div><div>How about "auxiliary compression operation"? Yeah, resolve is a bit of a bad name. </div><div>--Jason </div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"> > + * 1) Fast Clear: This operation writes the magic "clear" value to the > + * auxiliary surface. This operation will safely transition any slice > + * of a surface from any state to the clear state so long as the entire > + * slice is fast cleared at once. > + * > + * 2) Full Resolve: This operation combines the auxiliary surface data > + * with the primary surface data and writes the result to the primary. > + * For CCS resolves, this operation is destructive in the sense that it > + * also sets the auxiliary surface to the pass-through mode. For HiZ, > + * it is not destructive. > + * > + * 3) Partial Resolve: This operation considers blocks which are in the > + * "clear" state and writes the clear value directly into the primary or > + * auxiliary surface. Once this operation completes, the surface is > + * still compressed but no longer references the clear color. This > + * operation is only available for CCS. > + * > + * 4) Ambiguate: This operation throws away the current auxiliary data and > + * replaces it with the magic pass-through value. If an ambiguate > + * operation is performed when the primary surface does not contain 100% > + * of the data, data will be lost. This operation is only implemented > + * in hardware for depth where it is called a HiZ resolve. > + * > + * Not all operations are valid or useful in all states. The diagram below > + * contains a complete description of the states and all valid and useful > + * transitions except clear. > + * > + * Draw w/ Aux > + * +----------+ > + * | | > + * | +-------------+ Draw w/ Aux +-------------+ > + * +------>| Compressed |<---------------------| Clear | > + * | w/ Clear | | | > + * +-------------+ +-------------+ > + * | | | > + * Partial | | | > + * Resolve | | Full Resolve | > + * | +----------------------------+ | Full > + * | | | Resolve > + * Draw w/ aux | | | > + * +----------+ | | | > + * | | \|/ \|/ \|/ > + * | +-------------+ Full Resolve +-------------+ > + * +------>| Compressed |--------------------->| Resolved | > + * | w/o Clear |<---------------------| | > + * +-------------+ Draw w/ Aux +-------------+ > + * /|\ | | > + * | Draw | | Draw > + * | w/ Aux | | w/o Aux > + * | Ambiguate | | > + * | +----------------------------+ | > + * Draw w/o Aux | | | Draw w/o Aux > + * +----------+ | | | +----------+ > + * | | | \|/ \|/ | | > + * | +-------------+ Ambiguate +-------------+ | > + * +------>| Pass- |<---------------------| Aux |<------+ > + * | through | | Invalid | > + * +-------------+ +-------------+ > + * > + * > + * As referenced in the description of the different operations above, not all > + * auxiliary surface formats actually support all of the above modes. With > + * HiZ, for instance, does not have a partial resolve operation so the two > + * "compressed" modes are the same. With CCS, the resolve operation is > + * destructive and takes you directly to passthrough so the "resolved" state > + * doesn't really exist. However, if you consider the CCS resolve operation > + * as doing a resolve and then an ambiguate, the diagram is still accurate. > + */ </div></div>This comment is very helpful. </blockquote></div> </div></div>