[PATCH v7 0/3] drm: Add support for Cadence MHDP DPI/DP bridge and J721E wrapper.

[Swapnil Jakhade]

This patch series adds new DRM bridge driver for Cadence MHDP DPI/DP
bridge. The Cadence Display Port IP is also referred as MHDP (Mobile High
Definition Link, High-Definition Multimedia Interface, Display Port).
Cadence Display Port complies with VESA DisplayPort (DP) and embedded
Display Port (eDP) standards.

The MHDP bridge driver currently implements Single Stream Transport (SST)
mode. It also adds Texas Instruments j721e SoC specific wrapper and adds
the device tree bindings in YAML format.

Some of the features that will be added later on include (but are not
limited to):
- Power Management (PM) support: We will implement the PM functions in
  next stage once there will be a stable driver in upstream
- Converting to connector bridge operations: This is not supported
  currently because of dependency on TIDSS driver which has some
  limitations in supporting new model
- Audio and MST support

The patch series has three patches in the below sequence:
1. 0001-dt-bindings-drm-bridge-Document-Cadence-MHDP-brid.patch
Documents the bindings in yaml format.
2. 0002-drm-bridge-Add-support-for-Cadence-MHDP-DPI-DP-br.patch
This patch adds new DRM bridge driver for Cadence MHDP Display Port.
The patch implements support for single stream transport mode.
3. 0003-drm-bridge-cdns-mhdp-Add-j721e-wrapper.patch
Adds Texas Instruments (TI) j721e wrapper for MHDP. The wrapper configures
MHDP clocks and muxes as required by SoC.

This patch series is dependent on PHY patch series [1] to add new PHY APIs
to get/set PHY attributes which is under review and not merged yet.

[1] https://lkml.org/lkml/2020/7/17/158

Version History:

v7:

In 1/3
- No change

In 2/3
- Switch to atomic versions of bridge operations
- Implement atomic_check() handler to perform all validation checks
- Add struct cdns_mhdp_bridge_state with subclassed bridge state
- Use PHY API[1] to get PHY attributes instead of reading from PHY DT node
- Updated HPD handling and link configuration in IRQ handler
- Add "link_mutex" protecting the access to all the link parameters
- Add support to check and print FW version information
- Add separate function to initialize host parameters to simplify probe
- Use waitqueue instead of manual loop in cdns_mhdp_remove
- Add forward declarations and header files in cdns-mhdp-core.h file
- Use bool instead of single bit values in struct cdns_mhdp_device
- Fix for other minor comments given for v6 patches

In 3/3
- Use of_device_is_compatible() to set compatible string specific values
- Move mhdp_ti_j721e_ops structure to cdns-mhdp-j721e.c
- Remove duplicate Copyright message
- Remove CONFIG_DRM_CDNS_MHDP_J721E check
- Add Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

v6:
- Added minor fixes in YAML file.
- Added Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
  to the YAML patch.
- Removed all the FIXME comments which are invalid in drm driver.
- Reduced the mailbox timeout from 5s to 2s.
- Added Reviewed-by: Tomi Valkeinen <tomi.valkeinen at ti.com>
  to the 003-drm-mhdp-add-j721e-wrapper patch.
- Added Signed-off all the module authors.
- Fixed the compiler error Reported-by: kbuild test robot <lkp at intel.com>.

v5:
- Added Signed-off-by: Jyri Sarha <jsarha at ti.com> tag to
  the code patches.

v4:
- Added SPDX dual license tag to YAML bindings.
- Corrected indentation of the child node properties.
- Removed the maxItems in the conditional statement.
- Add Reviewed-by: Rob Herring <robh at kernel.org> tag to the
  Document Cadence MHDP bridge bindings patch.
- Renamed the DRM driver executable name from mhdp8546 to cdns-mhdp in
  Makefile.
- Renamed the DRM driver and header file from cdns-mhdp to cdns-mhdp-core.

v3:
- Added if / then clause to validate that the reg length is proper
  based on the value of the compatible property.
- Updated phy property description in YAML to a generic one.
- Renamed num_lanes and max_bit_rate property strings to cdns,num-lanes
  and cdns,max-bit-rate.

v2:
- Use enum in compatible property of YAML file.
- Add reg-names property to YAML file
- Add minItems and maxItems to reg property in YAML.
- Remove cdns_mhdp_link_probe function to remove
  duplication of reading dpcd capabilities.

Swapnil Jakhade (2):
  drm: bridge: Add support for Cadence MHDP DPI/DP bridge
  drm: bridge: cdns-mhdp: Add j721e wrapper

Yuti Amonkar (1):
  dt-bindings: drm/bridge: Document Cadence MHDP bridge bindings

 .../bindings/display/bridge/cdns,mhdp.yaml    |  127 +
 drivers/gpu/drm/bridge/Kconfig                |   24 +
 drivers/gpu/drm/bridge/Makefile               |    7 +
 drivers/gpu/drm/bridge/cdns-mhdp-core.c       | 2508 +++++++++++++++++
 drivers/gpu/drm/bridge/cdns-mhdp-core.h       |  397 +++
 drivers/gpu/drm/bridge/cdns-mhdp-j721e.c      |   75 +
 drivers/gpu/drm/bridge/cdns-mhdp-j721e.h      |   19 +
 7 files changed, 3157 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/bridge/cdns,mhdp.yaml
 create mode 100644 drivers/gpu/drm/bridge/cdns-mhdp-core.c
 create mode 100644 drivers/gpu/drm/bridge/cdns-mhdp-core.h
 create mode 100644 drivers/gpu/drm/bridge/cdns-mhdp-j721e.c
 create mode 100644 drivers/gpu/drm/bridge/cdns-mhdp-j721e.h

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2.26.1