Hi Uwe,
On Tue, Jan 18, 2022 at 11:41:19PM +0100, Uwe Kleine-König wrote:
> On 1/18/22 21:47, Laurent Pinchart wrote:
> > On Tue, Jan 18, 2022 at 12:00:50PM -0800, Florian Fainelli wrote:
> >> On 1/18/22 11:45 AM, Jean-Michel Hautbois wrote:
> >>> This is also needed for camera and display support.
> >>> I tested it successfully with imx219 + unicam on mainline.
> >>
> >> Thanks for testing, can you reply with a Tested-by tag so it could be
> >> applied to the commit message when this gets picked up?
> >
> > Well, this also points out that there's an issue: if the mux is needed
> > for other devices, it shouldn't be in bcm2711-rpi-cm4-io.dts :-) We
> > could move it to bcm2711-rpi.dtsi (so far all bcm2711-based boards use
> > either I/O pins 0+1 or 44+45)
>
> If I understand correctly it's not used on rpi-4-b, so bcm2711-rpi.dtsi
> would be wrong.
rpi-4-b muxes I2C0 on pins 0+1 and 44+45. The latter is wired to the
camera connector, and used for the camera sensor. Same thing on rpi-cm4.
rpi-400 has no camera connector, but I believe the display I2C bus is
also on pins 44+45 (at least according to the downstream DT sources,
rpi-400 muxes I2C0 on 0+1 and 44+45 too).
> > , or move it to per-board files.
>
> It is in an board file now?! So I don't understand your suggestion here.
Sorry, I meant have it in per-board files, not more it there.
> > In the
> > latter case, instead of duplicating the same block everywhere, it could
> > be moved to a .dtsi included in those board files. This is what the
> > downstream kernel does.
>
> How does it call the dtsi file? I wonder if that is sensible expecting
> that the devices on the bus are different for different boards?!
Downstream has a bcm283x-rpi-i2c0mux_0_44.dtsi that just contains
&i2c0mux {
pinctrl-0 = <&i2c0_gpio0>;
pinctrl-1 = <&i2c0_gpio44>;
};
with i2c0mux defined in bcm283x.dtsi as
i2c0mux: i2c0mux {
compatible = "i2c-mux-pinctrl";
#address-cells = <1>;
#size-cells = <0>;
i2c-parent = <&i2c0if>;
pinctrl-names = "i2c0", "i2c_csi_dsi";
status = "disabled";
i2c0: i2c@0 {
reg = <0>;
#address-cells = <1>;
#size-cells = <0>;
};
i2c_csi_dsi: i2c@1 {
reg = <1>;
#address-cells = <1>;
#size-cells = <0>;
};
};
The following board files #include "bcm283x-rpi-i2c0mux_0_44.dtsi":
- bcm2710-rpi-3-b.dts
- bcm2710-rpi-3-b-plus.dts
- bcm2710-rpi-zero-2-w.dts
- bcm2711-rpi-400.dts
- bcm2711-rpi-4-b.dts
- bcm2711-rpi-4-b.dts.orig
- bcm2711-rpi-cm4.dts
We don't have to replicate the exact same mechanism and use the same
names, but for rpi-4-b and rpi-cm4, to enable camera support (which
we're working on, Jean-Michel has posted a driver for the Unicam CSI-2
receiver to the linux-media mailing list, the ISP will follow), we need
the mux. Given that those two boards have a camera connector, I think it
makes sense to define the mux in a different file than
bcm2711-rpi-cm4-io.dts. The RTC node can stay in bcm2711-rpi-cm4-io.dts.
--
Regards,
Laurent Pinchart
