[PATCH 0/4] drm/meson: add support for Amlogic Video FBC

From: Neil Armstrong
Date: Thu Feb 20 2020 - 11:28:04 EST

Amlogic uses a proprietary lossless image compression protocol and format
for their hardware video codec accelerators, either video decoders or
video input encoders.

It considerably reduces memory bandwidth while writing and reading
frames in memory.

The underlying storage is considered to be 3 components, 8bit or 10-bit
per component, YCbCr 420, single plane :

This modifier will be notably added to DMA-BUF frames imported from the V4L2
Amlogic VDEC decoder.

At least two options are supported :
- Scatter mode: the buffer is filled with a IOMMU scatter table referring
to the encoder current memory layout. This mode if more efficient in terms
of memory allocation but frames are not dumpable and only valid during until
the buffer is freed and back in control of the encoder
- Memory saving: when the pixel bpp is 8b, the size of the superblock can
be reduced, thus saving memory.

This serie adds the missing register, updated the FBC decoder registers
content to be committed by the crtc code.

The Amlogic FBC has been tested with compressed content from the Amlogic
HW VP9 decoder on S905X (GXL), S905D2 (G12A) and S905X3 (SM1) in 8bit
(Scatter+Mem Saving on G12A/SM1, Mem Saving on GXL) and 10bit
(Scatter on G12A/SM1, default on GXL).

It's expected to work as-is on GXM and G12B SoCs.

Neil Armstrong (4):
drm/fourcc: Add modifier definitions for describing Amlogic Video
Framebuffer Compression
drm/meson: add Amlogic Video FBC registers
drm/meson: overlay: setup overlay for Amlogic FBC
drm/meson: crtc: handle commit of Amlogic FBC frames

drivers/gpu/drm/meson/meson_crtc.c | 118 ++++++++---
drivers/gpu/drm/meson/meson_drv.h | 16 ++
drivers/gpu/drm/meson/meson_overlay.c | 257 +++++++++++++++++++++++-
drivers/gpu/drm/meson/meson_registers.h | 22 ++
include/uapi/drm/drm_fourcc.h | 56 ++++++
5 files changed, 431 insertions(+), 38 deletions(-)