[PATCH v2 00/14] Add DRM driver for Solomon SSD16xx e-paper display controllers

[Devarsh Thakkar]

This series adds a DRM driver for the Solomon Systech SSD16xx family of
e-paper display controllers (SSD1673, SSD1680, SSD1681, SSD1683), starting
with support for the Gooddisplay GDEY042T81, a 4.2" 400×300 black-and-white
e-paper panel driven by the SSD1683 controller.

The driver is designed and architected keeping the bi-stable nature
and low-power requirements of epaper display based systems in mind
along with having adequate flexibility to support varying use-case
requirements for the e-paper display use-cases.

The driver integrates with the DRM atomic modesetting framework and
supports:

  - SPI communication in both 4-wire mode (separate D/C GPIO) and
    3-wire mode (9-bit SPI with embedded D/C# bit)
  - Full 4-way rotation via the Data Entry Mode register, with no GPU
    or memory-copy overhead
  - Three independently selectable refresh waveforms: partial (~300–500 ms),
    full (~1.5–2 s), and fast (~1.0–1.5 s)
  - 3-colour BWR pixel classification for panels with a red RAM plane
  - Pixel format support: XRGB8888 (color path) and R1 (native 1bpp,
    zero-copy path)
  - Runtime PM with configurable autosuspend: the controller enters
    Mode 1 deep sleep (RAM retained) after an idle timeout, waking
    transparently on the next frame update
  - System suspend/resume: switches to Mode 2 deep sleep (maximum
    power savings) on system suspend and rebuilds the pipeline on resume
  - Runtime-configurable DRM plane properties for refresh mode, colour
    mode, and session control (clear-on-init/close/disable, init-refresh
    waveform); rotation is set at probe time from a device tree property,
    and border waveform uses a fixed per-panel default

Changes from v1[0]:
  - Restructured into 14 modular patches covering bindings, driver core,
    features, and platform integration (was 6 patches in v1)
  - Added comprehensive device-tree bindings support for vendor prefixes
    and SSD16xx controller configurations
  - Refactored driver architecture from drm/tiny panel driver to drm/solomon
    bridge driver
  - Switch to using GEM_SHMEM helpers
  - Refactored data entry mode implementation
  - Removed runtime-configurable rotation/border-waveform DRM properties and
    their module params; rotation is now set via device tree, and border
    waveform now uses an enhanced fixed per-panel default
  - Added support for Solomon SSD1677 controller variant
  - Improved session management with plane properties
  - Added comprehensive power management support
  - Support for panels with reversed RAM X order
  - Dropped RGB888, RGB565, R8, NV12, NV16, YUYV, and UYVY format support;
    driver now only exposes XRGB8888 and R1

This has been tested against my development branch [1] using attached
test suite [2] and logs[3], individual results[4] and result summary[5] uploaded.

[0]: [V1 patch series]
https://lore.kernel.org/all/20260430183311.2978142-1-devarsht@xxxxxx/

[1]: [Development Branch]
https://github.com/devarsht/linux-next/tree/epaper_drm_misc_next_staging_27_09_26

[2]: [Test Suite]
https://github.com/devarsht/linux-next/tree/epaper_drm_misc_next_staging_27_09_26/tests_27sept_new

[3]: [Test Logs]
https://github.com/devarsht/linux-next/tree/epaper_drm_misc_next_staging_27_09_26/tests_27sept_new/logs

[4]: [Test Results]
https://github.com/devarsht/linux-next/tree/epaper_drm_misc_next_staging_27_09_26/tests_27sept_new/results

[5]: [Result Summary]
https://github.com/devarsht/linux-next/blob/epaper_drm_misc_next_staging_27_09_26/tests_27sept_new/results/run_all_20250529_190854.summary

Devarsh Thakkar (13):
  dt-bindings: vendor-prefixes: Add Dalian Good Display Co., Ltd.
  dt-bindings: display: Add Solomon SSD16xx e-paper controller binding
  dt-bindings: display: solomon,ssd16xx: Add Solomon SSD1677 controller
  drm/solomon: Add DRM driver for Solomon SSD16xx e-paper display
    controllers
  drm/solomon: ssd16xx: Add clear_on_init/close/disable session
    management
  drm/solomon: ssd16xx: Add support for Solomon SSD1677 controller
  drm/solomon: ssd16xx: Add power management support
  drm/solomon: ssd16xx: Expose refresh mode as plane property
  drm/solomon: ssd16xx: Expose color mode as plane property
  drm/solomon: ssd16xx: Expose session management as plane properties
  MAINTAINERS: Add entry for Solomon SSD16xx DRM driver
  arm64: defconfig: Enable DRM_SSD16XX for AM62L3 EVM
  arm64: dts: ti: Add AM62L3 EVM overlay for GDEY042T81 e-paper display

LiangCheng Wang (1):
  drm/solomon: ssd16xx: support panels whose RAM X order is reversed

 .../bindings/display/solomon,ssd16xx.yaml     |   88 +
 .../devicetree/bindings/vendor-prefixes.yaml  |    2 +
 MAINTAINERS                                   |    8 +
 arch/arm64/boot/dts/ti/Makefile               |    6 +
 .../ti/k3-am62l3-evm-epaper-gdey042t81.dtso   |   96 +
 arch/arm64/configs/defconfig                  |    1 +
 drivers/gpu/drm/solomon/Kconfig               |   13 +
 drivers/gpu/drm/solomon/Makefile              |    1 +
 drivers/gpu/drm/solomon/ssd16xx.c             | 2607 +++++++++++++++++
 9 files changed, 2822 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/solomon,ssd16xx.yaml
 create mode 100644 arch/arm64/boot/dts/ti/k3-am62l3-evm-epaper-gdey042t81.dtso
 create mode 100644 drivers/gpu/drm/solomon/ssd16xx.c

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2.39.1