radeon_drm.h: missing TILE_MODE definition?

[Alexandre Demers]

On Thu, 11 Feb 2016 at 10:30 Alex Deucher <alexdeucher at gmail.com> wrote:

> On Thu, Feb 11, 2016 at 12:23 AM, Alexandre Demers
> <alexandre.f.demers at gmail.com> wrote:
> > I was looking at /drivers/gpu/drm/radeon/atombios_crtc.c and at
> radeon_drm.h
> > (both under kernel and libdrm). I noticed that there seems to be a
> missing
> > TILE_MODE definition: under atombios_crtc, line 1289
> > (/drivers/gpu/drm/radeon/atombios_crtc.c#L1289), an unexplained value is
> > being used (index = 10;) compared to the rest of the code around where
> > defined variables are being used.
> >
> > Looking at the defined variables under radeon_drm.h, there is a missing
> > value in the tile index. Index 10 is missing. If it was defined, it
> could be
> > used in place of the numerical value at line 1289 under atombios_crtc.c.
> > According to the other names and usages, shouldn't there be a #define
> > SI_TILE_MODE_COLOR_2D_SCANOUT_8BPP 10? In fact, the equivalent of
> > SI_TILE_MODE_COLORD_2D_8BPP is CIK_TILE_MODE_COLOR_2D under CIK; under
> CIK,
> > there is a variable defined for index 10, which is
> > CIK_TILE_MODE_COLOR_2D_SCANOUT. Thus, I'd be inclined to think there
> should
> > really be a SI_TILE_MODE_COLOR_2D_SCANOUT_8BPP variable defined.
> >
> > I've been searching in the SI 3D register documentation and I couldn't
> find
> > a tile index table to relate to.
> >
> > Lastly, based on how the other "X_2D_SCANOUT_YBPP" variables are covered
> > under si_surface_sanity() (libdrm's radeon_surface.c), is it expected
> that
> > this index value (10) is not covered specifically. Should there be a
> "case
> > 1: *tile_mode = SI_TILE_MODE_COLOR_2D_SCANOUT_8BPP; break;" at line 1362,
> > before "case 2: ..."? Would it make sense?
> >
>
> I don't think it's a particularly useful case.  In practice I doubt it
> would ever be hit.  I guess it's for 8bpp greyscale.  The 3D engine
> can't render to indexed color or 332 surfaces.  If you aren't using
> the 3D engine, there's not much point in using tiling to begin with.
>
> Alex
>

Thanks for the answer.

At least, I'd like to add a "#define  SI_TILE_MODE_COLOR_2D_SCANOUT_8BPP
10;" (if that variable name makes sense, I'm open to any other more
meaningful name) just so we don't have a "index = 10" right there in the
middle of the code while other cases use defined variables: it is mostly
about consistency and readability of the code. Any objection?

Your comment is more about if this case/index value should be covered under
si_surface_sanity(). I'll trust you on the fact that it shouldn't be
encountered.

Cheers
Alexandre Demers
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