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

[Marcus Folkesson]

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 at gmail.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 at gmail.com>