Re: [PATCH 08/14] media: sunxi: Add support for the A31 MIPI CSI-2 controller

Maxime Ripard
2020-11-02T09:21:17Z

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On Fri, Oct 30, 2020 at 07:45:18PM -0300, Helen Koike wrote:
> On 10/23/20 2:45 PM, Paul Kocialkowski wrote:
> > The A31 MIPI CSI-2 controller is a dedicated MIPI CSI-2 controller
> > found on Allwinner SoCs such as the A31 and V3/V3s.
> >
> > It is a standalone block, connected to the CSI controller on one side
> > and to the MIPI D-PHY block on the other. It has a dedicated address
> > space, interrupt line and clock.
> >
> > Currently, the MIPI CSI-2 controller is hard-tied to a specific CSI
> > controller (CSI0) but newer SoCs (such as the V5) may allow switching
> > MIPI CSI-2 controllers between CSI controllers.
> >
> > It is represented as a V4L2 subdev to the CSI controller and takes a
> > MIPI CSI-2 sensor as its own subdev, all using the fwnode graph and
> > media controller API.
>
> Maybe this is a bad idea, but I was thinking:
> This driver basically just turn on/off and catch some interrupts for errors,
> and all the rest of v4l2 config you just forward to the next subdevice
> on the pipeline.
>
> So instead of exposing it as a subdevice, I was wondering if modeling
> this driver also through the phy subsystem wouldn't be cleaner, so
> you won't need all the v4l2 subdevice/topology boilerplate code that
> it seems you are not using (unless you have plans to add controls or
> some specific configuration on this node later).
>
> But this would require changes on the sun6i-csi driver.
>
> What do you think?

Eventually we'll need to filter the virtual channels / datatypes I
guess, so it's definitely valuable to have it in v4l2

Maxime

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