From: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
To: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
Jacopo Mondi <jacopo.mondi@ideasonboard.com>,
Francesco Dolcini <francesco@dolcini.it>,
Sakari Ailus <sakari.ailus@iki.fi>,
Marcel Ziswiler <marcel@ziswiler.com>,
linux-media@vger.kernel.org, kernel@pengutronix.de,
Francesco Dolcini <francesco.dolcini@toradex.com>,
Aishwarya Kothari <aishwarya.kothari@toradex.com>,
Marcel Ziswiler <marcel.ziswiler@toradex.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Steve Longerbeam <slongerbeam@gmail.com>,
linux-kernel@vger.kernel.org,
Marco Felsch <m.felsch@pengutronix.de>
Subject: Re: [PATCH v2] media: i2c: ov5640: Implement get_mbus_config
Date: Mon, 20 Mar 2023 13:47:12 +0100 [thread overview]
Message-ID: <20230320124712.q67dqlldkqsdwyke@uno.localdomain> (raw)
In-Reply-To: <9b4f0896a3a3e97b44197de263c30f0d31333abd.camel@pengutronix.de>
Hi Philipp
On Mon, Mar 20, 2023 at 12:26:26PM +0100, Philipp Zabel wrote:
> On Mo, 2023-03-20 at 11:55 +0200, Laurent Pinchart wrote:
> > On Mon, Mar 20, 2023 at 11:37:33AM +0200, Sakari Ailus wrote:
> > > 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.
> >
> > If I recall correctly, the IPU driver calls .g_mbus_config() on the
> > camera sensor to get the number of lanes, as it can't get it from its
> > own endpoint. That's a hack, and as Jacopo proposed, calling
> > .g_mbus_config() on the CSI-2 RX would be better, as the CSI-2 RX driver
> > can then get the value from its own endpoint, without requiring all
> > sensor drivers to implement .g_mbus_config().
>
> The IPU driver doesn't call get_mbus_config, the CSI-2 RX driver does
Am I confusing IPU CSI with CSI-2 ?
https://elixir.bootlin.com/linux/latest/source/drivers/staging/media/imx/imx-media-csi.c#L211
> (csi2_get_active_lanes in imx6-mipi-csi2.c). It could just fall back to
> looking at its own endpoint if the upstream driver does not implement
> get_mbus_config.
>
> Of course that will only help if the DT contains this information and
> all connected lanes are active.
We should assume DTs are correct, otherwise we're screwed most of the
times...
>
> regards
> Philipp
next prev parent reply other threads:[~2023-03-20 12:47 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-06 6:36 [PATCH v2] media: i2c: ov5640: Implement get_mbus_config Marcel Ziswiler
2023-03-14 12:13 ` Sakari Ailus
2023-03-14 12:32 ` Francesco Dolcini
2023-03-14 12:45 ` Sakari Ailus
2023-03-14 12:59 ` Francesco Dolcini
2023-03-20 8:48 ` Jacopo Mondi
2023-03-20 9:00 ` Sakari Ailus
2023-03-20 9:26 ` Laurent Pinchart
2023-03-20 9:37 ` Sakari Ailus
2023-03-20 9:55 ` Laurent Pinchart
2023-03-20 10:15 ` Sakari Ailus
2023-03-20 13:32 ` Philipp Zabel
2023-03-20 14:00 ` Laurent Pinchart
2023-03-20 18:31 ` Dave Stevenson
2023-03-20 21:53 ` Laurent Pinchart
2023-03-20 21:53 ` Sakari Ailus
2023-03-20 11:26 ` Philipp Zabel
2023-03-20 12:47 ` Jacopo Mondi [this message]
2023-03-20 13:28 ` Philipp Zabel
2023-03-20 11:13 ` Francesco Dolcini
2023-03-22 13:53 ` Aishwarya Kothari
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