Re: [Mesa-dev] [PATCH 01/64] i965: Drop Max3DTextureLevels to 512 on Sandy Bridge and prior

[Ian Romanick]

On 06/16/2016 11:50 AM, Jason Ekstrand wrote:
> 
> 
> On Thu, Jun 16, 2016 at 11:43 AM, Ian Romanick  > wrote:
> 
> On 06/11/2016 09:02 AM, Jason Ekstrand wrote:
> > The RenderTargetViewExtent field of RENDER_SURFACE_STATE is supposed to 
> be
> > set to the depth of a 3-D texture when rendering.  Unfortunatley, that
>  Unfortunately
> 
> > field is only 9 bits on Sandy Bridge and prior so we can't actually bind
> > a 3-D texturing for rendering if it has depth > 512.  On Ivy Bridge, 
> this
> > field was bumpped to 11 bits so we can go all the way up to 2048.
> bumped
> 
> > Cc: "11.1 11.2 12.0"  >
> > ---
> >  src/mesa/drivers/dri/i965/brw_context.c | 5 -
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/src/mesa/drivers/dri/i965/brw_context.c 
> b/src/mesa/drivers/dri/i965/brw_context.c
> > index 7bbc128..3b11bef 100644
> > --- a/src/mesa/drivers/dri/i965/brw_context.c
> > +++ b/src/mesa/drivers/dri/i965/brw_context.c
> > @@ -467,7 +467,10 @@ brw_initialize_context_constants(struct 
> brw_context *brw)
> > ctx->Const.MaxImageUnits = MAX_IMAGE_UNITS;
> > ctx->Const.MaxRenderbufferSize = 8192;
> > ctx->Const.MaxTextureLevels = MIN2(14 /* 8192 */, 
> MAX_TEXTURE_LEVELS);
> > -   ctx->Const.Max3DTextureLevels = 12; /* 2048 */
> > +   if (brw->gen >= 7)
> > +  ctx->Const.Max3DTextureLevels = 12; /* 2048 */
> > +   else
> > +  ctx->Const.Max3DTextureLevels = 10; /* 512 */
> 
> This should use ?: like MaxArrayTextureLayers below.
> 
> This was increased from 512 to 2048 in 2014 in commit 06b047eb.  There
> was some assertion in the commit message that the Windows driver was
> already advertising 2048.  There is no mention, however, of which
> hardware the Windows driver was checked on.  In the related bug report
> (https://bugs.freedesktop.org/show_bug.cgi?id=74130), Ken says, "All
> Gen4+ systems support 2048x2048 3D textures, so we could just bump the
> limit."
> 
> It sounds like this may be a temporary fix, and we need a work around
> for rendering to slices > 9?
> 
> It's a bit more subtle than that, I'm afraid.  The current gen4 render
> target setup code (which isn't used on SNB) can handle rendering to any
> layer of a 3-D texture regardless of size and SNB could be fixed up to
> do the same.  The problem is when you use layered rendering.  When doing
> layered rendering, we can only access at most 512 layers.  This means
> that we need to either limit the texture size or we need to give the
> user an incomplete framebuffer if they try and do layered rendering on a
> 3-D texture with more than 512 slices.  That's kind-of a nasty edge for
> applications to hit.

Oh yuck.  It is mean to give a spurious incomplete framebuffer, but
reducing a limit can make a previously working app fail... also mean.
I think there's a less-mean plan possible.  I believe these are the
facts:

 * Gen4 and Gen5 don't have layered rendering, so Max3DTextureLevels =
   12 should "just work" there.

 * According to 
http://feedback.wildfiregames.com/report/opengl/device/Intel%28R%29%20HD%20Graphics%203000,
   the Windows driver only supports OpenGL 3.1, so they never had the
   layered rendering issue.  They also advertise 2048 starting with
   driver version 9.17.10.2792.

 * In OpenGL ES and OpenGL Compatibility profile, there is no way to do
   layered rendering on SNB with our driver.

 * With a bit of work, we could handle 2048 on SNB for all non-layered
   rendering cases.

Assuming that's all correct, how about if we change the current patch to

   ctx->Const.Max3DTextureLevels = brw->gen == 6 ? 9 /* 512 */ : 12 /* 2048 */;

and add a release note.

For 12.next let's plan to do Gen4-style layer offsetting for SNB.  Then
change the limit setting code to

   ctx->Const.Max3DTextureLevels = brw->gen == 6 && ctx->API == API_OPENGL_CORE
  ? 9 /* 512 */ : 12 /* 2048 */;

We can also add a driconf option to force 2048.

A "patches welcome" follow-up would be to implement
GL_NV_deep_texture3D to expose width or height of 2048 with depth
limited to 512.

> --Jason
> 
> > ctx->Const.MaxCubeTextureLevels = 14; /* 8192 */
> > ctx->Const.MaxArrayTextureLayers = brw->gen >= 7 ? 2048 : 512;
> > ctx->Const.MaxTextureMbytes = 1536;
> >

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Re: [Mesa-dev] [PATCH 01/64] i965: Drop Max3DTextureLevels to 512 on Sandy Bridge and prior

[Jason Ekstrand]

On Thu, Jun 16, 2016 at 11:43 AM, Ian Romanick  wrote:

> On 06/11/2016 09:02 AM, Jason Ekstrand wrote:
> > The RenderTargetViewExtent field of RENDER_SURFACE_STATE is supposed to
> be
> > set to the depth of a 3-D texture when rendering.  Unfortunatley, that
>  Unfortunately
>
> > field is only 9 bits on Sandy Bridge and prior so we can't actually bind
> > a 3-D texturing for rendering if it has depth > 512.  On Ivy Bridge, this
> > field was bumpped to 11 bits so we can go all the way up to 2048.
> bumped
>
> > Cc: "11.1 11.2 12.0" 
> > ---
> >  src/mesa/drivers/dri/i965/brw_context.c | 5 -
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/src/mesa/drivers/dri/i965/brw_context.c
> b/src/mesa/drivers/dri/i965/brw_context.c
> > index 7bbc128..3b11bef 100644
> > --- a/src/mesa/drivers/dri/i965/brw_context.c
> > +++ b/src/mesa/drivers/dri/i965/brw_context.c
> > @@ -467,7 +467,10 @@ brw_initialize_context_constants(struct brw_context
> *brw)
> > ctx->Const.MaxImageUnits = MAX_IMAGE_UNITS;
> > ctx->Const.MaxRenderbufferSize = 8192;
> > ctx->Const.MaxTextureLevels = MIN2(14 /* 8192 */,
> MAX_TEXTURE_LEVELS);
> > -   ctx->Const.Max3DTextureLevels = 12; /* 2048 */
> > +   if (brw->gen >= 7)
> > +  ctx->Const.Max3DTextureLevels = 12; /* 2048 */
> > +   else
> > +  ctx->Const.Max3DTextureLevels = 10; /* 512 */
>
> This should use ?: like MaxArrayTextureLayers below.
>
> This was increased from 512 to 2048 in 2014 in commit 06b047eb.  There
> was some assertion in the commit message that the Windows driver was
> already advertising 2048.  There is no mention, however, of which
> hardware the Windows driver was checked on.  In the related bug report
> (https://bugs.freedesktop.org/show_bug.cgi?id=74130), Ken says, "All
> Gen4+ systems support 2048x2048 3D textures, so we could just bump the
> limit."
>
> It sounds like this may be a temporary fix, and we need a work around
> for rendering to slices > 9?
>

It's a bit more subtle than that, I'm afraid.  The current gen4 render
target setup code (which isn't used on SNB) can handle rendering to any
layer of a 3-D texture regardless of size and SNB could be fixed up to do
the same.  The problem is when you use layered rendering.  When doing
layered rendering, we can only access at most 512 layers.  This means that
we need to either limit the texture size or we need to give the user an
incomplete framebuffer if they try and do layered rendering on a 3-D
texture with more than 512 slices.  That's kind-of a nasty edge for
applications to hit.

--Jason


>
> > ctx->Const.MaxCubeTextureLevels = 14; /* 8192 */
> > ctx->Const.MaxArrayTextureLayers = brw->gen >= 7 ? 2048 : 512;
> > ctx->Const.MaxTextureMbytes = 1536;
> >
>
>
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Re: [Mesa-dev] [PATCH 01/64] i965: Drop Max3DTextureLevels to 512 on Sandy Bridge and prior

[Ian Romanick]

On 06/11/2016 09:02 AM, Jason Ekstrand wrote:
> The RenderTargetViewExtent field of RENDER_SURFACE_STATE is supposed to be
> set to the depth of a 3-D texture when rendering.  Unfortunatley, that
 Unfortunately

> field is only 9 bits on Sandy Bridge and prior so we can't actually bind
> a 3-D texturing for rendering if it has depth > 512.  On Ivy Bridge, this
> field was bumpped to 11 bits so we can go all the way up to 2048.
bumped

> Cc: "11.1 11.2 12.0" 
> ---
>  src/mesa/drivers/dri/i965/brw_context.c | 5 -
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_context.c 
> b/src/mesa/drivers/dri/i965/brw_context.c
> index 7bbc128..3b11bef 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.c
> +++ b/src/mesa/drivers/dri/i965/brw_context.c
> @@ -467,7 +467,10 @@ brw_initialize_context_constants(struct brw_context *brw)
> ctx->Const.MaxImageUnits = MAX_IMAGE_UNITS;
> ctx->Const.MaxRenderbufferSize = 8192;
> ctx->Const.MaxTextureLevels = MIN2(14 /* 8192 */, MAX_TEXTURE_LEVELS);
> -   ctx->Const.Max3DTextureLevels = 12; /* 2048 */
> +   if (brw->gen >= 7)
> +  ctx->Const.Max3DTextureLevels = 12; /* 2048 */
> +   else
> +  ctx->Const.Max3DTextureLevels = 10; /* 512 */

This should use ?: like MaxArrayTextureLayers below.

This was increased from 512 to 2048 in 2014 in commit 06b047eb.  There
was some assertion in the commit message that the Windows driver was
already advertising 2048.  There is no mention, however, of which
hardware the Windows driver was checked on.  In the related bug report
(https://bugs.freedesktop.org/show_bug.cgi?id=74130), Ken says, "All
Gen4+ systems support 2048x2048 3D textures, so we could just bump the
limit."

It sounds like this may be a temporary fix, and we need a work around
for rendering to slices > 9?

> ctx->Const.MaxCubeTextureLevels = 14; /* 8192 */
> ctx->Const.MaxArrayTextureLayers = brw->gen >= 7 ? 2048 : 512;
> ctx->Const.MaxTextureMbytes = 1536;
> 

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[Mesa-dev] [PATCH 01/64] i965: Drop Max3DTextureLevels to 512 on Sandy Bridge and prior

[Jason Ekstrand]

The RenderTargetViewExtent field of RENDER_SURFACE_STATE is supposed to be
set to the depth of a 3-D texture when rendering.  Unfortunatley, that
field is only 9 bits on Sandy Bridge and prior so we can't actually bind
a 3-D texturing for rendering if it has depth > 512.  On Ivy Bridge, this
field was bumpped to 11 bits so we can go all the way up to 2048.

Cc: "11.1 11.2 12.0" 
---
 src/mesa/drivers/dri/i965/brw_context.c | 5 -
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c 
b/src/mesa/drivers/dri/i965/brw_context.c
index 7bbc128..3b11bef 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -467,7 +467,10 @@ brw_initialize_context_constants(struct brw_context *brw)
ctx->Const.MaxImageUnits = MAX_IMAGE_UNITS;
ctx->Const.MaxRenderbufferSize = 8192;
ctx->Const.MaxTextureLevels = MIN2(14 /* 8192 */, MAX_TEXTURE_LEVELS);
-   ctx->Const.Max3DTextureLevels = 12; /* 2048 */
+   if (brw->gen >= 7)
+  ctx->Const.Max3DTextureLevels = 12; /* 2048 */
+   else
+  ctx->Const.Max3DTextureLevels = 10; /* 512 */
ctx->Const.MaxCubeTextureLevels = 14; /* 8192 */
ctx->Const.MaxArrayTextureLayers = brw->gen >= 7 ? 2048 : 512;
ctx->Const.MaxTextureMbytes = 1536;
-- 
2.5.0.400.gff86faf

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