linux-kernel - Re: [PATCH v2] media: i2c: ov5640: Implement get_mbus

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Message-ID: <ZBgpXRtXcxg14OGv@kekkonen.localdomain>
Date:   Mon, 20 Mar 2023 11:37:33 +0200
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Jacopo Mondi <jacopo.mondi@...asonboard.com>,
        Francesco Dolcini <francesco@...cini.it>,
        Sakari Ailus <sakari.ailus@....fi>,
        Marcel Ziswiler <marcel@...wiler.com>,
        linux-media@...r.kernel.org,
        Philipp Zabel <p.zabel@...gutronix.de>, kernel@...gutronix.de,
        Francesco Dolcini <francesco.dolcini@...adex.com>,
        Aishwarya Kothari <aishwarya.kothari@...adex.com>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Steve Longerbeam <slongerbeam@...il.com>,
        linux-kernel@...r.kernel.org,
        Marco Felsch <m.felsch@...gutronix.de>
Subject: Re: [PATCH v2] media: i2c: ov5640: Implement get_mbus_config

Hi Laurent,

On Mon, Mar 20, 2023 at 11:26:02AM +0200, Laurent Pinchart wrote:
> In a (simplified) nutshell,
> 
> ---------+     +----------+     +---------+     +-----+     +-----+
> | Camera | --> | CSI-2 RX | --> | CSI2IPU | --> | Mux | --> | IPU |
> | Sensor |     |          |     | Gasket  |     |     |     |     |
> ---------+     +----------+     +---------+     +-----+     +-----+

Thank you, this is helpful.

I suppose the mux here at least won't actively do anything to the data. So
presumably its endpoint won't contain the active configuration, but its
superset.

> 
> All those blocks, except for the gasket, have a node in DT.
> 
> The IPU driver needs to know the number of CSI-2 data lanes, which is
> encoded in the data-lanes DT property present in both the sensor output
> endpoint and the CSI-2 RX input endpoint, but not the other endpoints in
> the pipeline.

This doesn't yet explain why the sensor would need to implement
get_mbus_config if its bus configuration remains constant.

I suppose those blocks in between would probably need something to convey
their active configuration from upstream sub-devices.

-- 
Kind regards,

Sakari Ailus