Re: [PATCH v3 0/7] drm/meson: add support for Amlogic Video FBC

[Neil Armstrong <narmstrong@baylibre.com>]

On 24/03/2020 15:20, Neil Armstrong wrote:
> 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 :
> - DRM_FORMAT_YUV420_8BIT
> - DRM_FORMAT_YUV420_10BIT
> 
> This modifier will be notably added to DMA-BUF frames imported from the V4L2
> Amlogic VDEC decoder.
> 
> At least two layout are supported :
> - Basic: composed of a body and a header
> - Scatter: 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
> 
> At least two options are supported :
> - 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.
> 
> Changes since v2 at [2]:
> - Added "BASIC" layout and moved the SCATTER mode as layout, making
>   BASIC and SCATTER layout exclusives
> - Moved the Memory Saving at bit 8 for options fields
> - Split fourcc and overlay patch to introduce basic, mem saving and then
>   scatter in separate patches
> - Added comment about "transferability" of the buffers
> 
> Changes since v1 at [1]:
> - s/VD1_AXI_SEL_AFB/VD1_AXI_SEL_AFBC/ into meson_registers.h
> 
> [1] https://patchwork.freedesktop.org/series/73722/#rev1
> [2] https://patchwork.freedesktop.org/series/73722/#rev2
> 
> Neil Armstrong (7):
>   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
>   drm/fourcc: amlogic: Add modifier definitions for Memory Saving option
>   drm/meson: overlay: setup overlay for Amlogic FBC Memory Saving mode
>   drm/meson: overlay: setup overlay for Amlogic FBC Scatter Memory
>     layout
> 
>  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           |  66 ++++++
>  5 files changed, 441 insertions(+), 38 deletions(-)
> 

Please ignore this serie, v4 has been sent.

Neil