Re: [PATCH v4 07/15] media: sun6i-csi: Add support for MIPI CSI-2 bridge input

[Maxime Ripard <maxime@cerno.tech>]

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On Thu, Dec 31, 2020 at 03:29:40PM +0100, Paul Kocialkowski wrote:
> The A31 CSI controller supports a MIPI CSI-2 bridge input, which has
> its own dedicated port in the fwnode graph.
> 
> Support for this input is added with this change:
> - two pads are defined for the media entity instead of one
>   and only one needs to be connected at a time;
> - the pads currently match the fwnode graph representation;
> - links are created between our pads and the subdevs for each
>   interface and are no longer immutable so that userspace can select
>   which interface to use in case both are bound to a subdev;
> - fwnode endpoints are parsed and stored for each interface;
> - the active subdev (and fwnode endpoint) is retrieved when validating
>   the media link at stream on time and cleared at stream off;
> - an error is raised if both links are active at the same time;
> - the MIPI interface bit is set if the MIPI CSI-2 bridge endpoint is
>   active.
> 
> In the future, the media entity representation might evolve to:
> - distinguish the internal parallel bridge and data formatter;
> - represent each of the 4 internal channels that can exist between
>   the parallel bridge (for BT656 time-multiplex) and MIPI CSI-2
>   (internal channels can be mapped to virtual channels);
> - connect the controller's output to the ISP instead of its
>   DMA engine.
> 
> Finally note that the MIPI CSI-2 bridges should not be linked in
> the fwnode graph unless they have a sensor subdev attached.
> 
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>

Acked-by: Maxime Ripard <mripard@kernel.org>

Maxime

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