On Tue, Sep 27, 2016 at 3:23 PM, Nanley Chery <nanleych...@gmail.com> wrote:
> On Tue, Sep 27, 2016 at 03:12:17PM -0700, Chad Versace wrote: > > On Tue 27 Sep 2016, Nanley Chery wrote: > > > On Tue, Sep 27, 2016 at 11:00:21AM -0700, Chad Versace wrote: > > > > > > As a consequence of that reasoning, we should set > 3DSTATE_CLEAR_PARAMS.DepthClearValueValid = 1 > > > > whenever hiz is enabled, even if we don't care about the actual > clear value. > The logic seems to imply that we can't trust the context to save/restore our depth clear value so we have to set it every time. At the very least, once per batch? In any case, I doubt there's all that much cost involved in emitting 3DSTATE_CLEAR_PARAMS so I don't think re-emitting it is that big of a deal. > > > > > > In the V3, I plan to emit that packet once at device initialization > time > > > HSW+, and to always emit it (in the expected location) for IVB/BYT. > Only > > > the latter platforms have the restriction that it must always be > > > programmed with the other depth/stencil commands. > > > > Is there any benefit to emitting it multiple times on ivb/byt? Does > > emitting once during initialization, as for hsw, also work for ivb/byt? > > If so, the code is cleaner if the two gens share the same workaround > > code. > > The benefit for emitting it multiple times on IVB/BYT is that we're > (possibly) following the oddly-worded programming note for the packet: > > From the IVB PRM Vol2P1, 11.5.5.4 3DSTATE_CLEAR_PARAMS: > > 3DSTATE_CLEAR_PARAMS must always be programmed in the along with > the other Depth/Stencil state commands(i.e. 3DSTATE_DEPTH_BUFFER, > 3DSTATE_STENCIL_BUFFER, or 3DSTATE_HIER_DEPTH_BUFFER) > > HSW+ doesn't have this restriction, so we're free to only do it once. >
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