What are you actually trying to achieve? Scaling say 1920x1080 to 960x540 and just averaging the the four pixels together?
The firmware display stack is deprecated, so there are definite limits to any support efforts. We won't be changing the range or operation of the scaling filters.
The vc4 kernel driver currently only offers the Mitchell Netravali filter, partly as the standard property in DRM to configure scaling filters is very limited (enum drm_scaling_filter introduced in 2020 defines DEFAULT and NEAREST_NEIGHBOUR), and partly that very few people actually care.
Having had a quick look, adding Nearest Neighbour to the stored kernels, and adding the per plane option to allow selecting it, is fairly straightforward. It only needs the extra filter to be defined around https://github.com/raspberrypi/linux/bl ... hvs.c#L469, and then update the relevant kernel offsets around https://github.com/raspberrypi/linux/bl ... ne.c#L1550 based on a new plane property created with drm_plane_create_scaling_filter_property(). Doing so isn't the highest of priorities though.
The firmware display stack is deprecated, so there are definite limits to any support efforts. We won't be changing the range or operation of the scaling filters.
The vc4 kernel driver currently only offers the Mitchell Netravali filter, partly as the standard property in DRM to configure scaling filters is very limited (enum drm_scaling_filter introduced in 2020 defines DEFAULT and NEAREST_NEIGHBOUR), and partly that very few people actually care.
Having had a quick look, adding Nearest Neighbour to the stored kernels, and adding the per plane option to allow selecting it, is fairly straightforward. It only needs the extra filter to be defined around https://github.com/raspberrypi/linux/bl ... hvs.c#L469, and then update the relevant kernel offsets around https://github.com/raspberrypi/linux/bl ... ne.c#L1550 based on a new plane property created with drm_plane_create_scaling_filter_property(). Doing so isn't the highest of priorities though.
Statistics: Posted by 6by9 — Thu Jul 25, 2024 11:31 am
