oRework of my previous patchset which added support for GEM buffers backed by non-coherent memory to the ingenic-drm driver.
Having GEM buffers backed by non-coherent memory is interesting in the particular case where it is faster to render to a non-coherent buffer then sync the data cache, than to render to a write-combine buffer, and (by extension) much faster than using a shadow buffer. This is true for instance on some Ingenic SoCs, where even simple blits (e.g. memcpy) are about three times faster using this method.
For the record, a previous patchset was accepted for 5.10 then had to be reverted, as it conflicted with some changes made to the DMA API.
The first two patches add support for cached GEM buffers in the DRM core, the third patch adds support for this functionality in the ingenic-drm driver for the JZ4770 SoC.
Cheers, -Paul
Paul Cercueil (3): drm: Add support for GEM buffers backed by non-coherent memory drm: Add and export function drm_gem_cma_sync_data drm/ingenic: Add option to alloc cached GEM buffers
drivers/gpu/drm/drm_gem_cma_helper.c | 96 ++++++++++++++++++++++- drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 56 ++++++++++++- drivers/gpu/drm/ingenic/ingenic-ipu.c | 18 ++++- include/drm/drm_gem_cma_helper.h | 12 ++- 4 files changed, 171 insertions(+), 11 deletions(-)