On Mon, 2021-08-02 at 20:12 +0800, Eizan Miyamoto wrote:

Broadly, this patch (1) adds a driver for various MTK MDP components
to
go alongside the main MTK MDP driver, and (2) hooks them all together
using the component framework.

(1) Up until now, the MTK MDP driver controls 8 devices in the device
tree on its own. When running tests for the hardware video decoder,
we
found that the iommus and LARBs were not being properly configured.
To
configure them, a driver for each be added to mtk_mdp_comp so that
mtk_iommu_add_device() can (eventually) be called from
dma_configure()
inside really_probe().

(2) The integration into the component framework allows us to defer
the
registration with the v4l2 subsystem until all the MDP-related
devices
have been probed, so that the relevant device node does not become
available until initialization of all the components is complete.

Some notes about how the component framework has been integrated:

- The driver for the rdma0 component serves double duty as the
"master"
  (aggregate) driver as well as a component driver. This is a non-
ideal
  compromise until a better solution is developed. This device is
  differentiated from the rest by checking for a "mediatek,vpu"
property
  in the device node.

- The list of mdp components remains hard-coded as
mtk_mdp_comp_dt_ids[]
  in mtk_mdp_core.c, and as mtk_mdp_comp_driver_dt_match[] in
  mtk_mdp_comp.c. This unfortunate duplication of information is
  addressed in a following patch in this series.

- The component driver calls component_add() for each device that is
  probed.

- In mtk_mdp_probe (the "master" device), we scan the device tree for
  any matching nodes against mtk_mdp_comp_dt_ids, and add component
  matches for them. The match criteria is a matching device node
  pointer.

- When the set of components devices that have been probed
corresponds
  with the list that is generated by the "master", the callback to
  mtk_mdp_master_bind() is made, which then calls the component bind
  functions.

- Inside mtk_mdp_master_bind(), once all the component bind functions
  have been called, we can then register our device to the v4l2
  subsystem.

- The call to pm_runtime_enable() in the master device is called
after
  all the components have been registered by their bind() functions
  called by mtk_mtp_master_bind(). As a result, the list of
components
  will not change while power management callbacks mtk_mdp_suspend()/
  resume() are accessing the list of components.

Signed-off-by: Eizan Miyamoto <redacted>
---

Reviewed-by: Houlong Wei <houlong.wei@mediatek.com>

(no changes since v1)

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