linux-kernel - [PATCH v3 0/3] drm/sitronix/st7920: Add support for the ST7920 controller

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Message-Id: <20251006-st7920-v3-0-4f89d656fa03@gmail.com>
Date: Mon, 06 Oct 2025 19:48:52 +0200
From: Iker Pedrosa <ikerpedrosam@...il.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Javier Martinez Canillas <javierm@...hat.com>, 
 Iker Pedrosa <ikerpedrosam@...il.com>
Cc: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
 devicetree@...r.kernel.org
Subject: [PATCH v3 0/3] drm/sitronix/st7920: Add support for the ST7920
 controller

This patch-series adds support for the Sitronix ST7920 controller, which
is a monochrome dot-matrix graphical LCD controller that has SPI and
parallel interfaces.

The st7920 driver only has support for SPI so displays using other
transport protocols are currently not supported.

* Patch #1 adds the driver.
* Patch #2 adds the DT binding schema.
* Patch #3 adds the MAINTAINERS information.

---
Changes in v3:
- Reorganize the patch documenting compatible (DT bindings) before their
  use.
- Drop reduntant information from DT bindings.
- Use a goto label to ensure drm_dev_exit() is called in the error path
  of drm_gem_fb_begin_cpu_access().
- Link to v2: https://lore.kernel.org/r/20250909-st7920-v2-0-409f4890fb5f@gmail.com

Changes in v2:
- Refactor SPI communication:
  * Internalize error handling and delays within the st7920_spi_write()
    helper.
  * Split the main SPI write function into smaller, command-specific
    helpers for clarity.
- Improve DRM/KMS logic:
  * Relocate CPU access calls (drm_gem_fb...) to the atomic_update hook.
  * Use standard DRM helpers (drm_crtc_helper_mode_valid_fixed and
    drm_connector_helper_get_modes_fixed) for mode validation and
    creation.
- General code cleanup:
  * Remove dead code related to ST7920_FAMILY.
  * Replace WARN_ON() with drm_WARN_ON_ONCE().
  * Ensure single variable assignments per line.
- Fix probe initialization order:
  * Move spi_set_drvdata() and st7920_init() to occur before device
    registration.
- Devicetree:
  * Update bindings to address feedback from review (e.g., reference
    common SPI properties).
- MAINTAINERS:
  * Add a proper commit message to the patch.
- Link to v1: https://lore.kernel.org/r/20250806-st7920-v1-0-64ab5a34f9a0@gmail.com
---

Signed-off-by: Iker Pedrosa <ikerpedrosam@...il.com>

---
Iker Pedrosa (3):
      dt-bindings: display: sitronix,st7920: Add DT schema
      drm: Add driver for Sitronix ST7920 LCD displays
      MAINTAINERS: Add entry for Sitronix ST7920 driver

 .../bindings/display/sitronix,st7920.yaml          |  50 ++
 MAINTAINERS                                        |   7 +
 drivers/gpu/drm/sitronix/Kconfig                   |  10 +
 drivers/gpu/drm/sitronix/Makefile                  |   1 +
 drivers/gpu/drm/sitronix/st7920.c                  | 892 +++++++++++++++++++++
 5 files changed, 960 insertions(+)
---
base-commit: c571cb70e1ed43ee543c70151e61a001ab2eefa2
change-id: 20250806-st7920-e7aba32b3ab6

Best regards,
-- 
Iker Pedrosa <ikerpedrosam@...il.com>