Hi Laurent, Am Samstag, 5. Februar 2022, 03:22:51 CET schrieb Laurent Pinchart: > Hi Alexander, > > On Fri, Feb 04, 2022 at 09:50:06AM +0100, Alexander Stein wrote: > > Am Donnerstag, 3. Februar 2022, 18:50:00 CET schrieb Jean-Michel Hautbois: > > > Introduce the dt-bindings documentation for bcm2835 CCP2/CSI2 Unicam > > > camera interface. Also add a MAINTAINERS entry for it. > > > > > > Signed-off-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx> > > > Signed-off-by: Naushir Patuck <naush@xxxxxxxxxxxxxxx> > > > Signed-off-by: Jean-Michel Hautbois > > > <jeanmichel.hautbois@xxxxxxxxxxxxxxxx> > > > > > > --- > > > v4: > > > - make MAINTAINERS its own patch > > > - describe the reg and clocks correctly > > > - use a vendor entry for the number of data lanes > > > --- > > > > > > .../bindings/media/brcm,bcm2835-unicam.yaml | 110 ++++++++++++++++++ > > > 1 file changed, 110 insertions(+) > > > create mode 100644 > > > > > > Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml > > > > > > diff --git > > > a/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml > > > b/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml new > > > file > > > mode 100644 > > > index 000000000000..0725a0267c60 > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml > > > @@ -0,0 +1,110 @@ > > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > > > +%YAML 1.2 > > > +--- > > > +$id: http://devicetree.org/schemas/media/brcm,bcm2835-unicam.yaml# > > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > > + > > > +title: Broadcom BCM283x Camera Interface (Unicam) > > > + > > > +maintainers: > > > + - Raspberry Pi Kernel Maintenance <kernel-list@xxxxxxxxxxxxxxx> > > > + > > > +description: |- > > > + The Unicam block on BCM283x SoCs is the receiver for either > > > + CSI-2 or CCP2 data from image sensors or similar devices. > > > + > > > + The main platform using this SoC is the Raspberry Pi family of > > > boards. > > > + On the Pi the VideoCore firmware can also control this hardware > > > block, > > > + and driving it from two different processors will cause issues. > > > + To avoid this, the firmware checks the device tree configuration > > > + during boot. If it finds device tree nodes starting by csi then > > > + it will stop the firmware accessing the block, and it can then > > > + safely be used via the device tree binding. > > > + > > > +properties: > > > + compatible: > > > + const: brcm,bcm2835-unicam > > > + > > > + reg: > > > + items: > > > + - description: Unicam block. > > > + - description: Clock Manager Image (CMI) block. > > > + > > > + interrupts: > > > + maxItems: 1 > > > + > > > + clocks: > > > + items: > > > + - description: Clock to drive the LP state machine of Unicam. > > > + - description: Clock for the vpu (core clock). > > > + > > > + clock-names: > > > + items: > > > + - const: lp > > > + - const: vpu > > > + > > > + power-domains: > > > + items: > > > + - description: Unicam power domain > > > + > > > + brcm,num-data-lanes: > > > + $ref: /schemas/types.yaml#/definitions/uint32 > > > + enum: [ 2, 4 ] > > > + description: Number of data lanes on the csi bus > > > > There is already data-lanes in > > Documentation/devicetree/bindings/media/video- interfaces.yaml. AFAICS > > these two are identical. Can't the video- > > interface.yaml be used for this? I'm no expert TBH. > > This is the number of data lanes that the Unicam instance supports. > There are two Unicam instances, and they can have 2 or 4 data lanes > depending on the SoC. The data-lanes endpoint property indicates the > number of lanes used on a particular board. Thanks for the explanation. Isn't this something which could be derived from the compatible, e.g. having 2 different ones for 2 and 4 lanes respectively? See [1] for a similar situation in the SPI subsystem. I don't have a strong opinion, just want to share my feedback. Regards, Alexander [1] https://patchwork.kernel.org/project/spi-devel-general/patch/ 20211207104114.2720764-1-alexander.stein@xxxxxxxxxxxxxxx/#24641405
