[Mesa-dev] [PATCH v3] i965: Fix calculation of layers array length for isl_view

[Danylo Piliaiev]

Hi Ilia, Jason,

All these cases are indeed could induce confusion,
I'll try to explain all of them:

Texture is not layered:
     Layers: 1
     Base Layer: %layer of image unit% + %layer of texture view%

Layered 3D texture:
     Layers: Entire level is bound, texture view does not affect layers 
of it
     Base Layer: 0

Layered non 3D texture (Array):
     Immutable (it's a texture view, see _mesa_set_texture_view_state):
         Layers: correct values of MinLayer and NumLayers is baked into 
texObject in texture_view and in _mesa_set_texture_view_state
         Base Layer: MinLayer

     Mutable (MinLayer is always 0 since it can be set only via texture 
view which makes texture immutable):
         Layers: array_len
         Base Layer: 0

So while the code from my pov should work it could be presented better.
However I'm not sure what will be better:

     } else if (obj->Immutable) {
         base_layer = obj->MinLayer;
         num_layers = obj->NumLayers;
     } else {
         base_layer = 0;
         num_layers = mt->surf.logical_level0_px.array_len;
     }

Or always calculate base_layer as "obj->MinLayer + u->_Layer" before the 
conditions,
     which will look slightly misleading and induce questions of why we 
don't subtract them from array_len.

What do you think?

Thanks!

On 11/14/18 12:01 AM, Ilia Mirkin wrote:
> On Tue, Nov 13, 2018 at 4:53 PM Jason Ekstrand <jason at jlekstrand.net> wrote:
>> On Mon, Sep 10, 2018 at 10:21 AM Danylo Piliaiev <danylo.piliaiev at gmail.com> wrote:
>>> Handle all cases in calculation of layers count for isl_view
>>> taking into account texture view and image unit.
>>> st_convert_image was taken as a reference.
>>>
>>> When u->Layered is true the whole level is taken with respect to
>>> image view. In other case only one layer is taken.
>>>
>>> v3: (Józef Kucia and Ilia Mirkin)
>>>      - Rewrote patch by taking st_convert_image as a reference
>>>      - Removed now unused get_image_num_layers function
>>>      - Changed commit message
>>>
>>> Fixes: 5a8c8903
>>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107856
>>>
>>> Signed-off-by: Danylo Piliaiev <danylo.piliaiev at globallogic.com>
>>> ---
>>>   .../drivers/dri/i965/brw_wm_surface_state.c   | 32 ++++++++++---------
>>>   1 file changed, 17 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
>>> index 944762ec46..9bfe6e2037 100644
>>> --- a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
>>> +++ b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
>>> @@ -1499,18 +1499,6 @@ update_buffer_image_param(struct brw_context *brw,
>>>      param->stride[0] = _mesa_get_format_bytes(u->_ActualFormat);
>>>   }
>>>
>>> -static unsigned
>>> -get_image_num_layers(const struct intel_mipmap_tree *mt, GLenum target,
>>> -                     unsigned level)
>>> -{
>>> -   if (target == GL_TEXTURE_CUBE_MAP)
>>> -      return 6;
>>> -
>>> -   return target == GL_TEXTURE_3D ?
>>> -      minify(mt->surf.logical_level0_px.depth, level) :
>>> -      mt->surf.logical_level0_px.array_len;
>>> -}
>>> -
>>>   static void
>>>   update_image_surface(struct brw_context *brw,
>>>                        struct gl_image_unit *u,
>>> @@ -1541,14 +1529,28 @@ update_image_surface(struct brw_context *brw,
>>>         } else {
>>>            struct intel_texture_object *intel_obj = intel_texture_object(obj);
>>>            struct intel_mipmap_tree *mt = intel_obj->mt;
>>> -         const unsigned num_layers = u->Layered ?
>>> -            get_image_num_layers(mt, obj->Target, u->Level) : 1;
>>> +
>>> +         unsigned base_layer, num_layers;
>>> +         if (u->Layered) {
>>> +            if (obj->Target == GL_TEXTURE_3D) {
>>> +               base_layer = 0;
>>> +               num_layers = minify(mt->surf.logical_level0_px.depth, u->Level);
>>> +            } else {
>>> +               base_layer = obj->MinLayer;
>>> +               num_layers = obj->Immutable ?
>>> +                                obj->NumLayers :
>>> +                                mt->surf.logical_level0_px.array_len;
>>
>> Doesn't this need to be array_len - base_layer?  I'm not sure on the others without digging.
> Probably not intuitively obvious, but MinLayer/NumLayers are only set
> for Immutable textures.
>
>    -ilia