Hi,
Here's a V2 of my patchset that attempts to clean up the current situation with DSI/DBI panels drivers, and tinyDRM.
For the record, here is a small sum-up of the current situation:
- the current MIPI DBI code (drivers/gpu/drm/drm_mipi_dbi.c) is lagging way behind the MIPI DSI code (drivers/gpu/drm/drm_mipi_dsi.c). While the DSI code adds a proper bus support, with support for host drivers and client devices, there is no such thing with the DBI code. As such, it is currently impossible to write a standard DRM panel driver for a DBI panel.
- Even if the MIPI DBI code was updated with a proper bus, many panels and MIPI controllers support both DSI and DBI, so it would be a pain to support them without resolving to duplicating each driver.
- The panel drivers written against the DBI code are all "tinyDRM" drivers, which means that they will register a full yet simple DRM driver, and cannot be used as regular DRM panels for a different DRM driver.
- These "tinyDRM" drivers all use SPI directly, even though the panels they're driving can work on other interfaces (e.g. i8080 bus). Which means that one driver written for e.g. a ILI9341 would not work if the control interface is not SPI.
- The "tinyDRM" common code is entangled with DBI and there is no clear separation between the two. It could very well be moved to a single "tinyDRM" driver that works with a DRM panel obtained from devicetree, because the only requirement is that the panel supports a few given DCS commands.
Noteworthy changes since V1:
* The DT binding document for the NV3052C panel has been updated with the feedback I got from V1. It now supports multiple power supplies.
* Instead of using macros to define bus types, we now have an enum mipi_dcs_bus_type.
* The WARN_ONE_ONCE() that were in place to check that the host and client drivers provided the DCS bus bitmask is gone, we just default to DSI instead.
* DBI/SPI driver code was moved out of drivers/gpu/drm/bridge/.
* The DBI/SPI driver is registered as a driver by each client if needed, they just call module_mpi_dbi_spi_driver(). This addresses the issue in V1 that compatible strings had to be added to two different places.
* NV3052C and ILI9341 panel drivers were updated to remove custom backlight handling, call drm_panel_{disable,unprepare} on module exit, and various small fixes.
For a more detailed changelog, see the header of each individual patch.
Paul Cercueil (6): dt-bindings: display: Document NewVision NV3052C DT node drm: dsi: Let host and device specify supported bus drm: Add SPI DBI host driver drm/tiny: Add TinyDRM for DSI/DBI panels drm/panel: Add panel driver for NewVision NV3052C based LCDs drm/panel: Add Ilitek ILI9341 DBI panel driver
.../display/panel/newvision,nv3052c.yaml | 100 ++++ drivers/gpu/drm/Kconfig | 8 + drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/drm_mipi_dbi_spi.c | 247 +++++++++ drivers/gpu/drm/drm_mipi_dsi.c | 9 + drivers/gpu/drm/panel/Kconfig | 18 + drivers/gpu/drm/panel/Makefile | 2 + drivers/gpu/drm/panel/panel-ilitek-ili9341.c | 318 +++++++++++ .../gpu/drm/panel/panel-newvision-nv3052c.c | 510 ++++++++++++++++++ drivers/gpu/drm/tiny/Kconfig | 8 + drivers/gpu/drm/tiny/Makefile | 1 + drivers/gpu/drm/tiny/tiny-dsi.c | 266 +++++++++ include/drm/drm_mipi_dbi_spi.h | 42 ++ include/drm/drm_mipi_dsi.h | 44 ++ 14 files changed, 1574 insertions(+) create mode 100644 Documentation/devicetree/bindings/display/panel/newvision,nv3052c.yaml create mode 100644 drivers/gpu/drm/drm_mipi_dbi_spi.c create mode 100644 drivers/gpu/drm/panel/panel-ilitek-ili9341.c create mode 100644 drivers/gpu/drm/panel/panel-newvision-nv3052c.c create mode 100644 drivers/gpu/drm/tiny/tiny-dsi.c create mode 100644 include/drm/drm_mipi_dbi_spi.h