linux-kernel - Re: [PATCH v6 0/6] drm/meson: add support for Amlogic Video FBC

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Message-ID: <25032a93-8bd5-91ad-6ab8-0fb2c74f40fb@baylibre.com>
Date:   Mon, 4 May 2020 17:07:38 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     daniel@...ll.ch, dri-devel@...ts.freedesktop.org
Cc:     linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 0/6] drm/meson: add support for Amlogic Video FBC

Hi Daniel,

On 21/04/2020 18:15, 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.

Is the fourcc DRM_FORMAT_MOD_ definition correct now ? It includes the changes I proposed on the
v5 thread.

Thanks,

Neil

> 
> 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 v5 at [5]:
> - merged all fourcc patches in 1
> - fixed fourcc definition to have only a single DRM_MOD_
> - fixed 2 checkpatch issues
> 
> Changes since v4 at [4]:
> - added layout and options mask
> - cosmetic changes in fourcc.h
> - fixed mod check using the masks
> - fixed plane apply using the masks
> 
> Changes since v3 at [3]:
> - added dropped fourcc patch for scatter
> - fixed build of last patch
> 
> 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
> [3] https://patchwork.freedesktop.org/series/73722/#rev3
> [4] https://patchwork.freedesktop.org/series/73722/#rev4
> [4] https://patchwork.freedesktop.org/series/73722/#rev5
> 
> Neil Armstrong (6):
>   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: overlay: setup overlay for Amlogic FBC Memory Saving mode
>   drm/meson: overlay: setup overlay for Amlogic FBC Scatter Memory
>     layout
>   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   | 290 +++++++++++++++++++++++-
>  drivers/gpu/drm/meson/meson_registers.h |  22 ++
>  include/uapi/drm/drm_fourcc.h           |  74 ++++++
>  5 files changed, 482 insertions(+), 38 deletions(-)
>