[PATCH v3 16/50] drm: Add helper to create a connector for a chain of bridges

[Boris Brezillon]

On Wed, 11 Dec 2019 00:57:16 +0200
Laurent Pinchart <laurent.pinchart at ideasonboard.com> wrote:

> Most bridge drivers create a DRM connector to model the connector at the
> output of the bridge. This model is historical and has worked pretty
> well so far, but causes several issues:
> 
> - It prevents supporting more complex display pipelines where DRM
> connector operations are split over multiple components. For instance a
> pipeline with a bridge connected to the DDC signals to read EDID data,
> and another one connected to the HPD signal to detect connection and
> disconnection, will not be possible to support through this model.
> 
> - It requires every bridge driver to implement similar connector
> handling code, resulting in code duplication.
> 
> - It assumes that a bridge will either be wired to a connector or to
> another bridge, but doesn't support bridges that can be used in both
> positions very well (although there is some ad-hoc support for this in
> the analogix_dp bridge driver).
> 
> In order to solve these issues, ownership of the connector needs to be
> moved to the display controller driver.
> 
> To avoid code duplication in display controller drivers, add a new
> helper to create and manage a DRM connector backed by a chain of
> bridges. All connector operations are delegating to the appropriate
> bridge in the chain.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

Reviewed-by: Boris Brezillon <boris.brezillon at collabora.com>