[Mesa-dev] [PATCH] r600: shader CF_OP_VTX also doesn't use the EOP bit.

[Dave Airlie]

On 17 November 2017 at 08:00, Gert Wollny <gw.fossdev at gmail.com> wrote:
> Am Mittwoch, den 15.11.2017, 11:28 +1000 schrieb Dave Airlie:
>> On 15 November 2017 at 04:50, Gert Wollny <gw.fossdev at gmail.com>
>> wrote:
>> > Although the EOP bit is documented for the vertex fetch clause, it
>> > is not
>> > properly interpreted. As a result the piglit
>> >   spec/arb_tessellation_shader/execution/trivial-tess-gs_no-gs-
>> > inputs creates a TESS_EVAL shader that does not have an EOP clause,
>> > which might result in a GPU lockup.
>> >
>> > This patch forces an additional CF_OP_NOP group like it is already
>> > done for other final CF_OP groups.
>>
>> Although I think this is probably a good safety thing to add, I've
>> sent a patch that should make it unneeded, it would be good if you
>> could test it.
>
> Regardless o this, I wonder why with do CF_OP_VTK and CF_OP_TEX not
> emit the EOP bit on evergreen? The documentation says it is supported,
> and when I apply below path (changed white spaces to fit the mail
> size), then I don't see any lock-ups, the sb disassembler reports the
> EOP flag, I don't get valgrind errors in sb, and no piglit regressions.
>

Looks like you found the actual bug there, the fact we don't emit the eop bit
is probably responsible for lots of higher up workarounds.

Dave.

> best,
> Gert
>
> --- a/src/gallium/drivers/r600/eg_asm.c
> +++ b/src/gallium/drivers/r600/eg_asm.c
> @@ -71,10 +69,13 @@ int eg_bytecode_cf_build(struct r600_bytecode *bc,
> struct r600_bytecode_cf *cf)
>         } else if (cfop->flags & CF_CLAUSE) {
>              /* CF_TEX/VTX (CF_ALU already handled above) */
>                bc->bytecode[id++] = S_SQ_CF_WORD0_ADDR(cf->addr >> 1);
> -              bc->bytecode[id++] = S_SQ_CF_WORD1_CF_INST(opcode) |
> +              bc->bytecode[id] = S_SQ_CF_WORD1_CF_INST(opcode) |
>                              S_SQ_CF_WORD1_BARRIER(1) |
>                              S_SQ_CF_WORD1_VALID_PIXEL_MODE(cf->vpm) |
>                              S_SQ_CF_WORD1_COUNT((cf->ndw / 4) - 1);
> +             if (bc->chip_class == EVERGREEN) /* no EOP on cayman */
> +                    bc->bytecode[id] |=
>          S_SQ_CF_ALLOC_EXPORT_WORD1_END_OF_PROGRAM(cf->end_of_program);
> +            id++;
>         } else if (cfop->flags & CF_EXP) {
>                  /* EXPORT instructions */
>                  bc->bytecode[id++] =
> S_SQ_CF_ALLOC_EXPORT_WORD0_RW_GPR(cf->output.gpr) |