[PATCH v3 0/7] drm: Add driver for Solomon SSD130X OLED displays

[Javier Martinez Canillas <javierm@redhat.com>]

This patch series adds a DRM driver for the Solomon OLED SSD1305, SSD1306,
SSD1307 and SSD1309 displays. It is a port of the ssd1307fb fbdev driver.

Using the DRM fb emulation, all the tests from Geert Uytterhoeven's fbtest
(https://git.kernel.org/pub/scm/linux/kernel/git/geert/fbtest.git) passes.

I've also tested it using the display as a VT output and even though fbcon
seems to work, it is mostly unusable on a 128x64 SSD1306 display.

This is a v3 that addresses all the issues pointed in v2. Thanks a lot
to everyone that gave me feedback and reviews.

Patch #1 splits per-line conversion logic in drm_fb_xrgb8888_to_gray8() to
a separate drm_fb_xrgb8888_to_gray8_line() helper function.

Patch #2 adds two new helpers, drm_fb_gray8_to_mono_reversed() to convert
from grayscale to monochrome and a drm_fb_xrgb8888_to_mono_reversed() to
convert from XR24 to monochrome. The latter internally converts each line
first to gray8 and then to reversed monochrome.

Patch #3 adds the driver. This only has the core support but doesn't have
any bus specific code, separate drivers are needed for the transport used.

Patch #4 adds a driver to use the I2C bus to communicate with the device
and patch #5 adds a similar driver for SPI. This one is a WIP and wasn't
tested. I'm including for people to test and modify for their displays.

Patch #6 just adds a MAINTAINERS entry for the DRM driver and patch #7
adds myself as a co-maintainer of the existing Device Tree binding for
ssd1307fb, since the same is shared between the fbdev and DRM drivers.

Best regards,
Javier

Changes in v3:
- Add a drm_fb_xrgb8888_to_gray8_line() helper function (Thomas Zimmermann)
- Also add a drm_fb_xrgb8888_to_mono_reversed() helper (Thomas Zimmermann)
- Split lines copy to drm_fb_gray8_to_mono_reversed_line() (Thomas Zimmermann)
- Handle case where the source buffer is not aligned to 8 (Thomas Zimmermann)
- Move driver from tiny sub-dir to drivers/gpu/drm/solomon (Sam Ravnborg)
- Split driver in a bus agnostic core and bus specific (Andy Shevchenko)
- Use regmap to access the chip registers (Andy Shevchenko)
- Remove unnecessary blank lines (Andy Shevchenko)
- Remove unneeded inline specifier in functions (Andy Shevchenko)
- Add a comment about always returning a single mode (Andy Shevchenko)
- Change write command logic to use do while loop (Andy Shevchenko)
- Use "firmware description" instead of "device tree" (Andy Shevchenko)
- Use return foo() instead of returning the return value (Andy Shevchenko)
- Don't split lines longer than 80 chars if makes less readable (Andy Shevchenko)
- Remove redundant else statements in .mode_valid callback (Andy Shevchenko)
- Rename powero{n,ff}() functions to power_o{n,ff)() (Andy Shevchenko)
- Use dev_err_probe() to prevent spam logs on probe deferral (Andy Shevchenko)
- Remove ',' after sentinel terminator in array (Andy Shevchenko)
- Fix a bug when doing partial updates (Geert Uytterhoeven)
- Add a separate driver for SSD130X chips I2C support (Andy Shevchenko)
- Add a separate driver for SSD130X chips SPI support (Andy Shevchenko)
- Adapt MAINTAINERS entry to point to the new drivers/gpu/drm/solomon directory.

Changes in v2:
- Drop patch that was adding a DRM_MODE_CONNECTOR_I2C type.
- Invert order of backlight {en,dis}able and display {on,off} (Sam Ravnborg)
- Don't clear the screen and turn on display on probe (Sam Ravnborg)
- Use backlight_get_brightness() macro to get BL brightness (Sam Ravnborg)
- Use dev managed version of devm_backlight_device_register() (Sam Ravnborg)
- Use dev_name(dev) for backlight name instead of an array (Sam Ravnborg)
- Drop the .get_brightness callback since isn't needed  (Sam Ravnborg)
- Rename driver to ssd130x since supports a display family (Thomas Zimmermann)
- Drop the TINY prefix from the Kconfig symbol (Thomas Zimmermann)
- Sort the Kconfig symbol dependencies alphabetically (Thomas Zimmermann)
- Rename struct ssd130x_array to struct ssd130x_i2c_msg (Thomas Zimmermann)
- Rename struct ssd130x_i2c_msg .type member to .cmd (Thomas Zimmermann)
- Use sizeof(*foo) instead of sizeof(struct foo) (Thomas Zimmermann)
- Use struct_size() macro to calculate sizeof(*foo) + len (Thomas Zimmermann)
- Use kcalloc() instead of kmalloc_array() + memset() (Thomas Zimmermann)
- Use shadow plane helpers virtual screen support (Thomas Zimmermann)
- Remove unused goto label in ssd1307_fb_blit_rect() (Thomas Zimmermann)
- Use drm_set_preferred_mode() inset of manually set (Thomas Zimmermann)
- Use shadow plane helpers virtual screen support (Thomas Zimmermann)
- Remove unused goto label in ssd1307_fb_blit_rect() (Thomas Zimmermann)
- Use drm_set_preferred_mode() inset of manually set (Thomas Zimmermann)
- Reorganize code in probe to make it more legible (Thomas Zimmermann)
- ssd130x_write_cmd() uses varargs to simplify I2C code (Thomas Zimmermann)
- Move regulator/pwm init logic to display pipe enable callback.
- Add Sam Ravnborg's acked-by to patch adding a MAINTAINERS entry (Sam Ravnborg)
- Add myself as co-maintainer of the ssd1370fb DT binding (Sam Ravnborg).

Javier Martinez Canillas (7):
  drm/format-helper: Add drm_fb_xrgb8888_to_gray8_line()
  drm/format-helper: Add drm_fb_{xrgb8888,gray8}_to_mono_reversed()
  drm: Add driver for Solomon SSD130X OLED displays
  drm/solomon: Add SSD130X OLED displays I2C support
  (WIP) drm/solomon: Add SSD130X OLED displays SPI support
  MAINTAINERS: Add entry for Solomon SSD130X OLED displays DRM driver
  dt-bindings: display: ssd1307fb: Add myself as binding co-maintainer

 .../bindings/display/solomon,ssd1307fb.yaml   |   1 +
 MAINTAINERS                                   |   7 +
 drivers/gpu/drm/Kconfig                       |   2 +
 drivers/gpu/drm/Makefile                      |   1 +
 drivers/gpu/drm/drm_format_helper.c           | 188 +++-
 drivers/gpu/drm/solomon/Kconfig               |  30 +
 drivers/gpu/drm/solomon/Makefile              |   3 +
 drivers/gpu/drm/solomon/ssd130x-i2c.c         | 117 +++
 drivers/gpu/drm/solomon/ssd130x-spi.c         | 114 +++
 drivers/gpu/drm/solomon/ssd130x.c             | 823 ++++++++++++++++++
 drivers/gpu/drm/solomon/ssd130x.h             |  76 ++
 include/drm/drm_format_helper.h               |   8 +
 12 files changed, 1358 insertions(+), 12 deletions(-)
 create mode 100644 drivers/gpu/drm/solomon/Kconfig
 create mode 100644 drivers/gpu/drm/solomon/Makefile
 create mode 100644 drivers/gpu/drm/solomon/ssd130x-i2c.c
 create mode 100644 drivers/gpu/drm/solomon/ssd130x-spi.c
 create mode 100644 drivers/gpu/drm/solomon/ssd130x.c
 create mode 100644 drivers/gpu/drm/solomon/ssd130x.h

-- 
2.34.1