From: Maxime Ripard <maxime@cerno.tech>
To: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Cc: linux-media@vger.kernel.org, devicetree@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org,
linux-sunxi@googlegroups.com,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Rob Herring <robh+dt@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
Yong Deng <yong.deng@magewell.com>,
Kishon Vijay Abraham I <kishon@ti.com>,
Vinod Koul <vkoul@kernel.org>,
Helen Koike <helen.koike@collabora.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Philipp Zabel <p.zabel@pengutronix.de>,
Hans Verkuil <hans.verkuil@cisco.com>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
Hans Verkuil <hverkuil@xs4all.nl>,
kevin.lhopital@hotmail.com
Subject: Re: [PATCH 07/14] dt-bindings: media: i2c: Add A31 MIPI CSI-2 bindings documentation
Date: Wed, 4 Nov 2020 17:53:08 +0100 [thread overview]
Message-ID: <20201104165308.rcdxvzyj3kbiyfan@gilmour.lan> (raw)
In-Reply-To: <20201104104827.GD285779@aptenodytes>
[-- Attachment #1: Type: text/plain, Size: 6362 bytes --]
On Wed, Nov 04, 2020 at 11:48:27AM +0100, Paul Kocialkowski wrote:
> Hi,
>
> On Tue 27 Oct 20, 19:44, Maxime Ripard wrote:
> > On Tue, Oct 27, 2020 at 10:52:21AM +0100, Paul Kocialkowski wrote:
> > > Hi,
> > >
> > > On Mon 26 Oct 20, 17:14, Maxime Ripard wrote:
> > > > i2c? :)
> > >
> > > Oops, good catch!
> > >
> > > > On Fri, Oct 23, 2020 at 07:45:39PM +0200, Paul Kocialkowski wrote:
> > > > > This introduces YAML bindings documentation for the A31 MIPI CSI-2
> > > > > controller.
> > > > >
> > > > > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > > > > ---
> > > > > .../media/allwinner,sun6i-a31-mipi-csi2.yaml | 168 ++++++++++++++++++
> > > > > 1 file changed, 168 insertions(+)
> > > > > create mode 100644 Documentation/devicetree/bindings/media/allwinner,sun6i-a31-mipi-csi2.yaml
> > > > >
> > > > > diff --git a/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-mipi-csi2.yaml b/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-mipi-csi2.yaml
> > > > > new file mode 100644
> > > > > index 000000000000..9adc0bc27033
> > > > > --- /dev/null
> > > > > +++ b/Documentation/devicetree/bindings/media/allwinner,sun6i-a31-mipi-csi2.yaml
> > > > > @@ -0,0 +1,168 @@
> > > > > +# SPDX-License-Identifier: GPL-2.0
> > > > > +%YAML 1.2
> > > > > +---
> > > > > +$id: http://devicetree.org/schemas/media/allwinner,sun6i-a31-mipi-csi2.yaml#
> > > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > > +
> > > > > +title: Allwinner A31 MIPI CSI-2 Device Tree Bindings
> > > > > +
> > > > > +maintainers:
> > > > > + - Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > > > > +
> > > > > +properties:
> > > > > + compatible:
> > > > > + oneOf:
> > > > > + - const: allwinner,sun6i-a31-mipi-csi2
> > > > > + - items:
> > > > > + - const: allwinner,sun8i-v3s-mipi-csi2
> > > > > + - const: allwinner,sun6i-a31-mipi-csi2
> > > > > +
> > > > > + reg:
> > > > > + maxItems: 1
> > > > > +
> > > > > + interrupts:
> > > > > + maxItems: 1
> > > > > +
> > > > > + clocks:
> > > > > + items:
> > > > > + - description: Bus Clock
> > > > > + - description: Module Clock
> > > > > +
> > > > > + clock-names:
> > > > > + items:
> > > > > + - const: bus
> > > > > + - const: mod
> > > > > +
> > > > > + phys:
> > > > > + items:
> > > > > + - description: MIPI D-PHY
> > > > > +
> > > > > + phy-names:
> > > > > + items:
> > > > > + - const: dphy
> > > > > +
> > > > > + resets:
> > > > > + maxItems: 1
> > > > > +
> > > > > + # See ./video-interfaces.txt for details
> > > > > + ports:
> > > > > + type: object
> > > > > +
> > > > > + properties:
> > > > > + port@0:
> > > > > + type: object
> > > > > + description: Input port, connect to a MIPI CSI-2 sensor
> > > > > +
> > > > > + properties:
> > > > > + reg:
> > > > > + const: 0
> > > > > +
> > > > > + endpoint:
> > > > > + type: object
> > > > > +
> > > > > + properties:
> > > > > + remote-endpoint: true
> > > > > +
> > > > > + bus-type:
> > > > > + const: 4
> > > > > +
> > > > > + clock-lanes:
> > > > > + maxItems: 1
> > > > > +
> > > > > + data-lanes:
> > > > > + minItems: 1
> > > > > + maxItems: 4
> > > > > +
> > > > > + required:
> > > > > + - bus-type
> > > > > + - data-lanes
> > > > > + - remote-endpoint
> > > > > +
> > > > > + additionalProperties: false
> > > > > +
> > > > > + required:
> > > > > + - endpoint
> > > > > +
> > > > > + additionalProperties: false
> > > > > +
> > > > > + port@1:
> > > > > + type: object
> > > > > + description: Output port, connect to a CSI controller
> > > > > +
> > > > > + properties:
> > > > > + reg:
> > > > > + const: 1
> > > > > +
> > > > > + endpoint:
> > > > > + type: object
> > > > > +
> > > > > + properties:
> > > > > + remote-endpoint: true
> > > > > +
> > > > > + bus-type:
> > > > > + const: 4
> > > >
> > > > That one seems a bit weird. If the input and output ports are using the
> > > > same format, what is that "bridge" supposed to be doing?
> > >
> > > Fair enough. What this represents is the internal link (likely a FIFO) between
> > > the two controllers. It is definitely not a MIPI CSI-2 bus but there's no
> > > mbus type for an internal link (probably because it's not a bus after all).
> > >
> > > Note that on the CSI controller side, we need the bus-type to be set to 4 for it
> > > to properly select the MIPI CSI-2 input. So it just felt more logical to have
> > > the same on the other side of the endpoint. On the other hand, we can just
> > > remove it on the MIPI CSI-2 controller side since it won't check it and have it
> > > fallback to the unknown mbus type.
> > >
> > > But that would make the types inconsistent on the two sides of the link.
> > > I don't think V4L2 will complain about it at the moment, but it would also make
> > > sense that it does eventually.
> > >
> > > What do you think?
> >
> > There's still the same issue though, it doesn't make any sense that a
> > bridge doesn't change the bus type. If it really did, we wouldn't need
> > that in the first place.
>
> Yes I agreee.
>
> > What you want to check in your driver is whether the subdev you're
> > connected to has a sink pad that uses MIPI-CSI
>
> I'm not really sure that's possible, but if it is it would indeed be the most
> appropriate solution. If it's not, we still need to know that we need to feed
> from MIPI CSI-2 so I don't see any other option than report MIPI CSI-2 on both
> ends of MIPI CSI-2 controller.
>
> But there's still the question of what media bus type should be reported for
> the CSI <-> MIPI CSI-2 link. I'm fine with unknown but we could also add a
> generic internal bus type for this case.
I guess both questions would need to be discussed more on the v4l2 side.
Maxime
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next prev parent reply other threads:[~2020-11-04 16:53 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-23 17:45 [PATCH 00/14] Allwinner MIPI CSI-2 support for A31/V3s/A83T Paul Kocialkowski
2020-10-23 17:45 ` [PATCH 01/14] phy: Distinguish between Rx and Tx for MIPI D-PHY with submodes Paul Kocialkowski
2020-10-23 18:18 ` [linux-sunxi] " Jernej Škrabec
2020-10-24 8:31 ` Paul Kocialkowski
2020-10-30 22:44 ` Helen Koike
2020-10-23 17:45 ` [PATCH 02/14] phy: allwinner: phy-sun6i-mipi-dphy: Support D-PHY Rx mode for MIPI CSI-2 Paul Kocialkowski
2020-10-26 15:38 ` Maxime Ripard
2020-10-27 9:23 ` Paul Kocialkowski
2020-10-27 18:28 ` Maxime Ripard
2020-11-04 10:53 ` Paul Kocialkowski
2020-10-30 22:44 ` Helen Koike
2020-11-04 10:54 ` Paul Kocialkowski
2020-10-23 17:45 ` [PATCH 03/14] media: sun6i-csi: Support an optional dedicated memory pool Paul Kocialkowski
2020-10-26 15:41 ` Maxime Ripard
2020-10-27 9:26 ` Paul Kocialkowski
2020-10-23 17:45 ` [PATCH 04/14] media: sun6i-csi: Fix the image storage bpp for 10/12-bit Bayer formats Paul Kocialkowski
2020-10-30 22:45 ` Helen Koike
2020-11-04 10:56 ` Paul Kocialkowski
2020-10-23 17:45 ` [PATCH 05/14] media: sun6i-csi: Only configure the interface data width for parallel Paul Kocialkowski
2020-10-26 16:00 ` Maxime Ripard
2020-10-27 9:31 ` Paul Kocialkowski
2020-10-27 18:31 ` Maxime Ripard
2020-10-23 17:45 ` [PATCH 06/14] media: sun6i-csi: Support feeding from the MIPI CSI-2 controller Paul Kocialkowski
2020-10-23 17:45 ` [PATCH 07/14] dt-bindings: media: i2c: Add A31 MIPI CSI-2 bindings documentation Paul Kocialkowski
2020-10-26 16:14 ` Maxime Ripard
2020-10-27 9:52 ` Paul Kocialkowski
2020-10-27 18:44 ` Maxime Ripard
2020-11-04 10:48 ` Paul Kocialkowski
2020-11-04 16:53 ` Maxime Ripard [this message]
2020-10-30 16:33 ` Rob Herring
2020-10-30 16:56 ` Sakari Ailus
2020-10-23 17:45 ` [PATCH 08/14] media: sunxi: Add support for the A31 MIPI CSI-2 controller Paul Kocialkowski
2020-10-26 8:39 ` Dan Carpenter
2020-10-26 16:54 ` Maxime Ripard
2020-11-04 11:34 ` Paul Kocialkowski
2020-11-04 18:56 ` Maxime Ripard
2020-11-05 14:52 ` Paul Kocialkowski
2020-10-30 22:45 ` Helen Koike
2020-11-02 9:21 ` Maxime Ripard
2020-11-04 11:17 ` Paul Kocialkowski
2020-11-04 16:38 ` Helen Koike
2020-11-04 18:45 ` Maxime Ripard
2020-11-05 14:14 ` Helen Koike
2020-11-05 8:45 ` Sakari Ailus
2020-11-05 14:55 ` Paul Kocialkowski
2020-10-23 17:45 ` [PATCH 09/14] ARM: dts: sun8i: v3s: Add CSI0 camera interface node Paul Kocialkowski
2020-10-23 17:45 ` [PATCH 10/14] ARM: dts: sun8i: v3s: Add MIPI D-PHY and MIPI CSI-2 interface nodes Paul Kocialkowski
2020-10-26 16:55 ` Maxime Ripard
2020-10-23 17:45 ` [PATCH 11/14] dt-bindings: media: i2c: Add A83T MIPI CSI-2 bindings documentation Paul Kocialkowski
2020-10-26 16:56 ` Maxime Ripard
2020-11-04 10:33 ` Paul Kocialkowski
2020-11-05 8:48 ` Sakari Ailus
2020-10-23 17:45 ` [PATCH 12/14] media: sunxi: Add support for the A83T MIPI CSI-2 controller Paul Kocialkowski
2020-10-26 8:53 ` Dan Carpenter
2020-10-26 17:00 ` Maxime Ripard
2020-11-04 10:37 ` Paul Kocialkowski
2020-10-23 17:45 ` [PATCH 13/14] ARM: dts: sun8i: a83t: Add MIPI CSI-2 controller node Paul Kocialkowski
2020-10-23 17:45 ` [PATCH 14/14] media: sunxi: sun8i-a83t-mipi-csi2: Avoid using the (unsolicited) interrupt Paul Kocialkowski
2020-10-26 16:57 ` Maxime Ripard
2020-10-26 17:20 ` [PATCH 00/14] Allwinner MIPI CSI-2 support for A31/V3s/A83T Maxime Ripard
2020-10-30 22:44 ` Helen Koike
2020-11-02 9:17 ` Maxime Ripard
2020-11-04 11:11 ` Paul Kocialkowski
2020-11-04 11:14 ` Paul Kocialkowski
2020-11-04 16:36 ` Helen Koike
2020-11-05 14:58 ` Paul Kocialkowski
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