Re: [RFC][PATCH 0/5] Introduce drm scaling filter property

[Ville Syrjälä]

On Tue, Feb 25, 2020 at 12:35:40PM +0530, Pankaj Bharadiya wrote:
> Integer scaling (IS) is a nearest-neighbor upscaling technique that
> simply scales up the existing pixels by an integer (i.e., whole
> number) multiplier. Nearest-neighbor (NN) interpolation works by
> filling in the missing color values in the upscaled image with that of
> the coordinate-mapped nearest source pixel value.
> 
> Both IS and NN preserve the clarity of the original image. In
> contrast, traditional upscaling algorithms, such as bilinear or
> bicubic interpolation, result in blurry upscaled images because they
> employ interpolation techniques that smooth out the transition from
> one pixel to another.  Therefore, integer scaling is particularly
> useful for pixel art games that rely on sharp, blocky images to
> deliver their distinctive look.
> 
> Many gaming communities have been asking for integer-mode scaling
> support, some links and background:
> 
> https://software.intel.com/en-us/articles/integer-scaling-support-on-intel-graphics
> http://tanalin.com/en/articles/lossless-scaling/
> https://community.amd.com/thread/209107
> https://www.nvidia.com/en-us/geforce/forums/game-ready-drivers/13/1002/feature-request-nonblurry-upscaling-at-integer-rat/
> 
> This patch series -
>   - Introduces new scaling filter property to allow userspace to
>     select  the driver's default scaling filter or Nearest-neighbor(NN)
>     filter for scaling operations on crtc/plane.
>   - Implements and enable integer scaling for i915
> 
> Userspace patch series link: TBD.

That needs to be done or this will go nowhere.

> 
> Thanks to Shashank for initiating this work. His initial RFC can be
> found here [1]
> 
> [1] https://patchwork.freedesktop.org/patch/337082/
> 
> Modifications done in this series -
>    - refactored code and incorporated initial review comments and
>      added 2 scaling filter types (default and NN) to begin with.
>    - added scaling filter property support for planes and new API
>      helpers for drivers to setup this property.
>    - rewrote code to enable integer scaling and NN filter for i915
> 
> 
> Pankaj Bharadiya (5):
>   drm: Introduce scaling filter property
>   drm/drm-kms.rst: Add Scaling filter property documentation
>   drm/i915: Enable scaling filter for plane and pipe
>   drm/i915: Introduce scaling filter related registers and bit fields.
>   drm/i915/display: Add Nearest-neighbor based integer scaling support
> 
>  Documentation/gpu/drm-kms.rst                |   6 ++
>  drivers/gpu/drm/drm_atomic_uapi.c            |   8 ++
>  drivers/gpu/drm/drm_crtc.c                   |  16 +++
>  drivers/gpu/drm/drm_mode_config.c            |  13 +++
>  drivers/gpu/drm/drm_plane.c                  |  35 +++++++
>  drivers/gpu/drm/i915/display/intel_display.c | 100 ++++++++++++++++++-
>  drivers/gpu/drm/i915/display/intel_display.h |   2 +
>  drivers/gpu/drm/i915/display/intel_sprite.c  |  32 ++++--
>  drivers/gpu/drm/i915/i915_reg.h              |  21 ++++
>  include/drm/drm_crtc.h                       |  10 ++
>  include/drm/drm_mode_config.h                |   6 ++
>  include/drm/drm_plane.h                      |  14 +++
>  12 files changed, 252 insertions(+), 11 deletions(-)
> 
> -- 
> 2.23.0

-- 
Ville Syrjälä
Intel