[Mesa-dev] [PATCH 03/18] gallium/radeon: add a workaround when viewport state is used to force Z

[Marek Olšák]

On Fri, Aug 18, 2017 at 3:55 PM, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
> On 17.08.2017 20:31, Marek Olšák wrote:
>>
>> From: Marek Olšák <marek.olsak at amd.com>
>>
>> This will be needed by u_blitter.
>> ---
>>   src/gallium/drivers/radeon/r600_viewport.c | 23 +++++++++++++++++++++--
>>   1 file changed, 21 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/gallium/drivers/radeon/r600_viewport.c
>> b/src/gallium/drivers/radeon/r600_viewport.c
>> index 2de1382..f7fc536 100644
>> --- a/src/gallium/drivers/radeon/r600_viewport.c
>> +++ b/src/gallium/drivers/radeon/r600_viewport.c
>> @@ -316,50 +316,69 @@ static void r600_emit_viewports(struct
>> r600_common_context *rctx)
>>                 u_bit_scan_consecutive_range(&mask, &start, &count);
>>                 radeon_set_context_reg_seq(cs, R_02843C_PA_CL_VPORT_XSCALE
>> +
>>                                                start * 4 * 6, count * 6);
>>                 for (i = start; i < start+count; i++)
>>                         r600_emit_one_viewport(rctx, &states[i]);
>>         }
>>         rctx->viewports.dirty_mask = 0;
>>   }
>>   +static void r600_get_zmin_zmax(const struct pipe_viewport_state *vp,
>> +                              bool clip_halfz, float *zmin, float *zmax)
>> +{
>> +       /* For some reason, setting zmin == zmax breaks things.
>> +        * Setting zmin = 0 && zmin = 1 works around it.
>> +        * u_blitter sets scale = 0 && translate = Z to force a certain Z
>> +        * value. The clamp would have no effect anyway, but it would be
>> nice
>> +        * to know what the problem is with zmin == zmax.
>
>
> Weird rounding/floating point issues? Could the blitter just set scale = 1
> for the same effect? Seems like that would be less hacky...

Yes, scale = 1 works too and doesn't need the workaround.

Marek

>
> Cheers,
> Nicolai
>
>
>
>> +        */
>> +       if (vp->scale[2] == 0) {
>> +               assert(vp->translate[2] >= 0 && vp->translate[2] <= 1);
>> +               *zmin = 0;
>> +               *zmax = 1;
>> +               return;
>> +       }
>> +
>> +       util_viewport_zmin_zmax(vp, clip_halfz, zmin, zmax);
>> +}
>> +
>>   static void r600_emit_depth_ranges(struct r600_common_context *rctx)
>>   {
>>         struct radeon_winsys_cs *cs = rctx->gfx.cs;
>>         struct pipe_viewport_state *states = rctx->viewports.states;
>>         unsigned mask = rctx->viewports.depth_range_dirty_mask;
>>         float zmin, zmax;
>>         /* The simple case: Only 1 viewport is active. */
>>         if (!rctx->vs_writes_viewport_index) {
>>                 if (!(mask & 1))
>>                         return;
>>   -             util_viewport_zmin_zmax(&states[0], rctx->clip_halfz,
>> &zmin, &zmax);
>> +               r600_get_zmin_zmax(&states[0], rctx->clip_halfz, &zmin,
>> &zmax);
>>                 radeon_set_context_reg_seq(cs,
>> R_0282D0_PA_SC_VPORT_ZMIN_0, 2);
>>                 radeon_emit(cs, fui(zmin));
>>                 radeon_emit(cs, fui(zmax));
>>                 rctx->viewports.depth_range_dirty_mask &= ~1; /* clear one
>> bit */
>>                 return;
>>         }
>>         while (mask) {
>>                 int start, count, i;
>>                 u_bit_scan_consecutive_range(&mask, &start, &count);
>>                 radeon_set_context_reg_seq(cs, R_0282D0_PA_SC_VPORT_ZMIN_0
>> +
>>                                            start * 4 * 2, count * 2);
>>                 for (i = start; i < start+count; i++) {
>> -                       util_viewport_zmin_zmax(&states[i],
>> rctx->clip_halfz, &zmin, &zmax);
>> +                       r600_get_zmin_zmax(&states[i], rctx->clip_halfz,
>> &zmin, &zmax);
>>                         radeon_emit(cs, fui(zmin));
>>                         radeon_emit(cs, fui(zmax));
>>                 }
>>         }
>>         rctx->viewports.depth_range_dirty_mask = 0;
>>   }
>>     static void r600_emit_viewport_states(struct r600_common_context
>> *rctx,
>>                                       struct r600_atom *atom)
>>   {
>>
>
>
> --
> Lerne, wie die Welt wirklich ist,
> Aber vergiss niemals, wie sie sein sollte.