[Mesa-dev] [PATCH] r600g: pad IBs to a multiple of 4 DWs on r6xx

[Christian König]

Actually Type 2 packets are handled much faster on the R6xx compared to 
most type 3 packets, cause they are handled by the PFP/fetch hw and 
doesn't need to be forwarded to the ME.

Christian.

Am 06.09.2013 02:31, schrieb Dominik Behr:
> 0x80000000 is Type 2 NOP.
> You could make it a little better/faster by inserting single 
> multi-DWORD Type 3 NOP
> And pad to 8 DWORDs. CP fetches are 32 bytes each and R600 has 
> requires padding. Same with padding CP ring buffer updates to 32 bytes 
> (pad to 32bytes before you update CP_RB_WPTR).
>
>
> On Thu, Sep 5, 2013 at 3:56 PM, Marek Olšák <maraeo at gmail.com 
> <mailto:maraeo at gmail.com>> wrote:
>
>     Reviewed-by: Marek Olšák <marek.olsak at amd.com
>     <mailto:marek.olsak at amd.com>>
>
>     Though I'm not sure if 0x80000000 is correct.
>
>     Marek
>
>     On Wed, Sep 4, 2013 at 11:55 PM, Alex Deucher
>     <alexdeucher at gmail.com <mailto:alexdeucher at gmail.com>> wrote:
>     > IBs need to be a multiple of 4 dwords on r6xx asics
>     > to avoid a hw bug.
>     >
>     > Signed-off-by: Alex Deucher <alexander.deucher at amd.com
>     <mailto:alexander.deucher at amd.com>>
>     > CC: "9.2" <mesa-stable at lists.freedesktop.org
>     <mailto:mesa-stable at lists.freedesktop.org>>
>     > CC: "9.1" <mesa-stable at lists.freedesktop.org
>     <mailto:mesa-stable at lists.freedesktop.org>>
>     > ---
>     >  src/gallium/drivers/r600/r600_hw_context.c | 13 +++++++++++++
>     >  1 file changed, 13 insertions(+)
>     >
>     > diff --git a/src/gallium/drivers/r600/r600_hw_context.c
>     b/src/gallium/drivers/r600/r600_hw_context.c
>     > index 97b0f9c..0a219af 100644
>     > --- a/src/gallium/drivers/r600/r600_hw_context.c
>     > +++ b/src/gallium/drivers/r600/r600_hw_context.c
>     > @@ -347,6 +347,19 @@ void r600_context_flush(struct r600_context
>     *ctx, unsigned flags)
>     >                 flags |= RADEON_FLUSH_KEEP_TILING_FLAGS;
>     >         }
>     >
>     > +       /* Pad the GFX CS to a multiple of 4 dwords on rv6xx
>     > +        * to avoid a hw bug.
>     > +        */
>     > +       if (ctx->chip_class < R700) {
>     > +               unsigned i;
>     > +               unsigned padding_dw = 4 - cs->cdw % 4;
>     > +               if (padding_dw < 4) {
>     > +                       for (i = 0; i < padding_dw; i++) {
>     > + cs->buf[cs->cdw++] = 0x80000000;
>     > +                       }
>     > +               }
>     > +       }
>     > +
>     >         /* Flush the CS. */
>     > ctx->ws->cs_flush(ctx->rings.gfx.cs, flags,
>     ctx->screen->cs_count++);
>     >  }
>     > --
>     > 1.8.3.1
>     >
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