Thanks all for the input. I don't have an in-depth knowledge of the hardware either, though as far as we can see the hardware does expect that we pass min_index in the command stream. max_index is used to calculate the sizes in other command stream fields (which is not the same as pipe_draw_info.count). The existing lima-ng implementation does the same: https://github.com/limadriver-ng/lima/blob/660a940c8cc151fd886559233c1a22385ee5f254/limare/lib/gp.c#L584 (draw->vertex_start).
On Sat, Mar 17, 2018 at 7:23 PM, Ilia Mirkin <imir...@alum.mit.edu> wrote: > For an approximation, you can use the sizes of the bound vbo's to > guess a min/max index. See > https://cgit.freedesktop.org/mesa/mesa/tree/src/gallium/drivers/vc4/vc4_draw.c#n183 > for an example. I quickly played with porting something like that to mesa-lima but I don't think it can solve our problem. Apparently our bo currently have a fairly large fixed size so I'm not sure we can do an equivalent calculation using bo size. And then, min_index is required too. On Sat, Mar 24, 2018 at 10:32 PM, Marek Olšák <mar...@gmail.com> wrote: > Here is how to do it: > > if (max_index != ~0u) > // index bounds are valid; > else > // scan the index buffer manually; > > u_vbuf_get_minmax_index can be used for the scanning. mesa-lima currently does not use any vbuf function. And we currently can't call u_vbuf_get_minmax_index since it's static in u_vbuf.c. I suppose we can consider making u_vbuf_get_minmax_index public then. I tested this and it works for me. It's still a bit annoying since we need to create fields probably in lima_context (like vc4_context.max_index does) and use those instead of the ones in pipe_draw_info. But not a big problem I guess. We could submit this refactor when mesa-lima gets proposed upstream. Just for completeness, one other idea that came up was to define a new PIPE_CAP_xxx config used to override st_context.draw_needs_minmax_index, and set that in this driver. This way, pipe_draw_info would come correctly filled and we wouldn't need to explicitly assemble minmax indices during the driver draw_vbo. How does this sound compared to the other solution? _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
