[PATCH v3 0/7] drm/tegra: Add DSI and panel support

[Thierry Reding]

Hi,

This third version of the series reworks some aspects of DSI and panel
support. There is now a DSI bus type, which can be used to instantiate
devices that represent DSI peripherals and register controllers as DSI
hosts. This is currently somewhat DT-centric, but all hardware that I
have access to boots from DT, so I couldn't test any other code anyway
and decided to leave that up until someone actually needs it.

Patch 1 adds the DSI bus type, which provides functions to instantiate
DSI peripherals as devices that can be tied into Linux' driver model.
Similarly a DSI host can be created (or embedded within the private
structure of a DSI controller driver), which DSI peripherals can talk
to. It also exposes a DSI driver, which is essentially a very think
wrapper around the standard struct device_driver and allows to easily
match DSI drivers to DSI devices (again, only DT-style matching is
supported so far).

Patch 2 adds the DRM panel framework. Not much has changed since the
previous version. Mostly smaller fixes and a way to control the panel
brightness, which would usually be tied to a struct backlight_device
but doesn't necessarily have to be, so I provided separate accessors
that can be used by drivers as they see fit.

Patch 3 implements the simple panel driver. The most notable changes
since v2 are that the brightness accessors are now implemented if a
backlight device is associated with the panel. Furthermore the driver
now supports DSI devices using the new DSI infrastructure, which at
the same time sharing most of the code with the platform driver for
panels not connected via a bus, such as dumb RGB/LVDS panels.

An implementation of the panel support for Tegra is provided in patch 4.
Due to how DSI devices are instantiated (namely as children of the DSI
controller after it has been probed), panels are now hotpluggable at
runtime. This sounds less scary than it actually is. It merely means
that the code can deal with a panel not being present at probe time
(which will never be the case for DSI). Depending on load order the
panel might become available only until rather late, and there is code
to deal with that as well (by leveraging the hotplug detection mechanism
in DRM). I haven't been able to produce this case yet, so that that code
path is currently untested, but it should work...

Furthermore this patch exposes a "brightness" property to userspace that
can be used to control the backlight associated with a panel. The aim is
to provide a standard way for userspace to access the correct backlight
and not rely on some heuristic to determine the correct sysfs path to
use for backlight control.

Patch 5 implements a driver for the MIPI pad calibration hardware found
on Tegra SoCs. It isn't very relevant to the DSI patches but is included
here for the sake of completeness.

The DSI host implementation for Tegra SoCs is provided in patch 6. That
contains some code to configure the MIPI D-PHY which might be useful in
other drivers, but I've kept it in the Tegra driver for now. It is
nicely split into separate files so would be easy to move out if needed.

Patch 7 contains a work-in-progress implementation of DSI command mode
for Tegra. This isn't cleaned up yet and contains various hacks to make
it work. Also when run while the controller is in video mode and sending
image data, the switch back to video mode after the message has been
transferred doesn't work properly and causes the display to no longer
work. When run before switching to video mode, however, this seems to
work properly. Things like short writes respond with the proper trigger
message and such. The goal for this was to be able to identify panels
using their device descriptor block (DDB). Unfortunately the display
panel that I have reads back only zeros (the framing of the messages
looks correct, though), so I somewhat lost interest in making this work
correctly.

Eventually I could envision turning this into something much bigger. If
for instance somebody has access to a panel from which a proper DDB can
be read, generic helpers could be written around this and panels probed
not via DT but also directly by matching against the supplier and other
data found in the DDB. In the meantime I'll try to find out if I can get
access to such hardware so that I can finish this up properly.

Thierry

Thierry Reding (7):
  drm: Add DSI bus infrastructure
  drm: Add panel support
  drm/panel: Add simple panel support
  drm/tegra: Implement panel support
  gpu: host1x: Add MIPI pad calibration support
  drm/tegra: Add DSI support
  WIP: drm/tegra: Implement DSI transfers

 .../bindings/gpu/nvidia,tegra20-host1x.txt         |   16 +
 .../bindings/misc/nvidia,tegra114-mipi.txt         |   37 +
 .../devicetree/bindings/panel/auo,b101aw03.txt     |    7 +
 .../bindings/panel/chunghwa,claa101wb03.txt        |    7 +
 .../bindings/panel/panasonic,vvx10f004b00.txt      |    7 +
 .../devicetree/bindings/panel/simple-panel.txt     |   21 +
 drivers/gpu/drm/Kconfig                            |    6 +
 drivers/gpu/drm/Makefile                           |    4 +
 drivers/gpu/drm/drm_dsi.c                          |  306 ++++++
 drivers/gpu/drm/drm_panel.c                        |  100 ++
 drivers/gpu/drm/panel/Kconfig                      |   20 +
 drivers/gpu/drm/panel/Makefile                     |    1 +
 drivers/gpu/drm/panel/panel-simple.c               |  467 +++++++++
 drivers/gpu/drm/tegra/Kconfig                      |    2 +
 drivers/gpu/drm/tegra/Makefile                     |    2 +
 drivers/gpu/drm/tegra/dc.h                         |    2 +
 drivers/gpu/drm/tegra/drm.c                        |   10 +-
 drivers/gpu/drm/tegra/drm.h                        |    5 +
 drivers/gpu/drm/tegra/dsi.c                        | 1087 ++++++++++++++++++++
 drivers/gpu/drm/tegra/dsi.h                        |  134 +++
 drivers/gpu/drm/tegra/mipi-phy.c                   |  137 +++
 drivers/gpu/drm/tegra/mipi-phy.h                   |   65 ++
 drivers/gpu/drm/tegra/output.c                     |   95 +-
 drivers/gpu/host1x/Makefile                        |    1 +
 drivers/gpu/host1x/dev.c                           |   17 +-
 drivers/gpu/host1x/dev.h                           |    2 +
 drivers/gpu/host1x/mipi.c                          |  272 +++++
 include/drm/drm_dsi.h                              |  206 ++++
 include/drm/drm_panel.h                            |  114 ++
 include/linux/host1x.h                             |    6 +
 30 files changed, 3147 insertions(+), 9 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/misc/nvidia,tegra114-mipi.txt
 create mode 100644 Documentation/devicetree/bindings/panel/auo,b101aw03.txt
 create mode 100644 Documentation/devicetree/bindings/panel/chunghwa,claa101wb03.txt
 create mode 100644 Documentation/devicetree/bindings/panel/panasonic,vvx10f004b00.txt
 create mode 100644 Documentation/devicetree/bindings/panel/simple-panel.txt
 create mode 100644 drivers/gpu/drm/drm_dsi.c
 create mode 100644 drivers/gpu/drm/drm_panel.c
 create mode 100644 drivers/gpu/drm/panel/Kconfig
 create mode 100644 drivers/gpu/drm/panel/Makefile
 create mode 100644 drivers/gpu/drm/panel/panel-simple.c
 create mode 100644 drivers/gpu/drm/tegra/dsi.c
 create mode 100644 drivers/gpu/drm/tegra/dsi.h
 create mode 100644 drivers/gpu/drm/tegra/mipi-phy.c
 create mode 100644 drivers/gpu/drm/tegra/mipi-phy.h
 create mode 100644 drivers/gpu/host1x/mipi.c
 create mode 100644 include/drm/drm_dsi.h
 create mode 100644 include/drm/drm_panel.h

-- 
1.8.4.2