[Mesa-dev] [PATCH] radeonsi: Fix guardband computation for large render targets

[Marek Olšák]

Pushed, thanks!

Marek

On Tue, Feb 12, 2019 at 2:55 PM Oscar Blumberg <carnaval at 12-10e.me> wrote:

> Stop using 12.12 quantization for viewports that are not contained in
> the lower 4k corner of the render target as the hardware needs to keep
> both absolute and relative coordinates representable.
> ---
>  .../drivers/radeonsi/si_state_viewport.c      | 30 +++++++++++++++++--
>  1 file changed, 28 insertions(+), 2 deletions(-)
>
> diff --git a/src/gallium/drivers/radeonsi/si_state_viewport.c
> b/src/gallium/drivers/radeonsi/si_state_viewport.c
> index dac90df1c4f..64bb956b200 100644
> --- a/src/gallium/drivers/radeonsi/si_state_viewport.c
> +++ b/src/gallium/drivers/radeonsi/si_state_viewport.c
> @@ -185,6 +185,16 @@ static void si_emit_guardband(struct si_context *ctx)
>         const unsigned hw_screen_offset_alignment =
>                 ctx->chip_class >= VI ? 16 :
> MAX2(ctx->screen->se_tile_repeat, 16);
>
> +       /* Indexed by quantization modes */
> +       static unsigned max_viewport_size[] = {65535, 16383, 4095};
> +
> +       /* Ensure that the whole viewport stays representable in
> +        * absolute coordinates.
> +        * See comment in si_set_viewport_states.
> +        */
> +       assert(vp_as_scissor.maxx <=
> max_viewport_size[vp_as_scissor.quant_mode] &&
> +              vp_as_scissor.maxy <=
> max_viewport_size[vp_as_scissor.quant_mode]);
> +
>         hw_screen_offset_x = CLAMP(hw_screen_offset_x, 0,
> MAX_PA_SU_HARDWARE_SCREEN_OFFSET);
>         hw_screen_offset_y = CLAMP(hw_screen_offset_y, 0,
> MAX_PA_SU_HARDWARE_SCREEN_OFFSET);
>
> @@ -219,7 +229,6 @@ static void si_emit_guardband(struct si_context *ctx)
>          *
>          * The viewport range is [-max_viewport_size/2,
> max_viewport_size/2].
>          */
> -       static unsigned max_viewport_size[] = {65535, 16383, 4095};
>         assert(vp_as_scissor.quant_mode < ARRAY_SIZE(max_viewport_size));
>         max_range = max_viewport_size[vp_as_scissor.quant_mode] / 2;
>         left   = (-max_range - vp.translate[0]) / vp.scale[0];
> @@ -333,6 +342,8 @@ static void si_set_viewport_states(struct pipe_context
> *pctx,
>                 unsigned h = scissor->maxy - scissor->miny;
>                 unsigned max_extent = MAX2(w, h);
>
> +               int max_corner = MAX2(scissor->maxx, scissor->maxy);
> +
>                 unsigned center_x = (scissor->maxx + scissor->minx) / 2;
>                 unsigned center_y = (scissor->maxy + scissor->miny) / 2;
>                 unsigned max_center = MAX2(center_x, center_y);
> @@ -358,7 +369,22 @@ static void si_set_viewport_states(struct
> pipe_context *pctx,
>                 if (ctx->family == CHIP_RAVEN)
>                         max_extent = 16384; /* Use QUANT_MODE == 16_8. */
>
> -               if (max_extent <= 1024) /* 4K scanline area for guardband
> */
> +               /* Another constraint is that all coordinates in the
> viewport
> +                * are representable in fixed point with respect to the
> +                * surface origin.
> +                *
> +                * It means that PA_SU_HARDWARE_SCREEN_OFFSET can't be
> given
> +                * an offset that would make the upper corner of the
> viewport
> +                * greater than the maximum representable number post
> +                * quantization, ie 2^quant_bits.
> +                *
> +                * This does not matter for 14.10 and 16.8 formats since
> the
> +                * offset is already limited at 8k, but it means we can't
> use
> +                * 12.12 if we are drawing to some pixels outside the lower
> +                * 4k x 4k of the render target.
> +                */
> +
> +               if (max_extent <= 1024 && max_corner < 4096) /* 4K
> scanline area for guardband */
>                         scissor->quant_mode =
> SI_QUANT_MODE_12_12_FIXED_POINT_1_4096TH;
>                 else if (max_extent <= 4096) /* 16K scanline area for
> guardband */
>                         scissor->quant_mode =
> SI_QUANT_MODE_14_10_FIXED_POINT_1_1024TH;
> --
> 2.20.1
>
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> mesa-dev at lists.freedesktop.org
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