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Subject[PATCH v2 0/6] DSI/DBI, panel drivers, & tinyDRM v2

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

- 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

* 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


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