linux-kernel - [PATCH 0/5] drm/st7571-i2c: add support for grayscale xrgb8888

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Message-Id: <20250714-st7571-format-v1-0-a27e5112baff@gmail.com>
Date: Mon, 14 Jul 2025 10:03:58 +0200
From: Marcus Folkesson <marcus.folkesson@...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>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 devicetree@...r.kernel.org, Marcus Folkesson <marcus.folkesson@...il.com>
Subject: [PATCH 0/5] drm/st7571-i2c: add support for grayscale xrgb8888

The goal with this series is to add support for 2bit grayscale with
the xrgb8888 pixel format for the st7571 display controller.

The first patch only corrects a comment of the pixel format.

The next two patches adds support for inverting pixels. This is
necessary as the connected display may or may not use the "right" (0 =>
black, 1 => white) pixel format expected by the supported formats
(R1/R2/XRGB8888).

The forth patch adds a helper function (drm_fb_xrgb8888_to_gray2) to
convert xrgb8888 to gray2.
drm_fb_xrgb8888_to_mono() has been changed splitted into two functions
where the common part is used by both drm_fb_xrgb8888_to_mono and
drm_fb_xrgb8888_to_gray2.

The last path adds support for gray2 in the st7571 driver.
Compare the mono [1] and the gray2 [2] variants of our penguin.

[1] https://www.marcusfolkesson.se/gray2.png
[2] https://www.marcusfolkesson.se/xrgb8888.png

Signed-off-by: Marcus Folkesson <marcus.folkesson@...il.com>
---
Marcus Folkesson (5):
      drm/st7571-i2c: correct pixel data format description
      dt-bindings: display: sitronix,st7571: add optional inverted property
      drm/st7571-i2c: add support inverted pixel format
      drm/format-helper: introduce drm_fb_xrgb8888_to_gray2()
      drm/st7571-i2c: add support for 2bit grayscale for XRGB8888

 .../bindings/display/sitronix,st7571.yaml          |   5 +
 drivers/gpu/drm/drm_format_helper.c                | 148 +++++++++++++++------
 drivers/gpu/drm/sitronix/st7571-i2c.c              |  38 +++---
 include/drm/drm_format_helper.h                    |   4 +
 4 files changed, 135 insertions(+), 60 deletions(-)
---
base-commit: a6cfa4c8833944f8912c1fa7f95795753f6376ea
change-id: 20250520-st7571-format-2ce6badc48c6

Best regards,
-- 
Marcus Folkesson <marcus.folkesson@...il.com>