Hi Dave, On Mon, Mar 18, 2024 at 02:56:33PM +0000, Dave Stevenson wrote: > On Fri, 1 Mar 2024 at 21:32, Laurent Pinchart wrote: > > > > From: Uwe Kleine-König <uwe@xxxxxxxxxxxxxxxxx> > > > > BCM2711-based Raspberry Pi boards (4B, CM4 and 400) multiplex the I2C0 > > controller over two sets of pins, GPIO0+1 and GPIO44+45. The former is > > exposed on the 40-pin header, while the latter is used for the CSI and > > DSI connectors. > > It's true for all Pis that I2C0 is exposed over 2 sets of gpios. > Seeing as we want to support cameras on Pi0-3, is there a reason not > to include the mux on those? Simplicity :-) I got lost in the maze of differences in .dtsi files between the upstream and downstream kernels. Given that not all Pi's have device trees upstream, I decided to start simple(r). > Looking back I had started this way back in [1] with all the variants. > I thought I'd posted the v2 follow up, but can't find it. > The original Pi 1 models A & B were the annoyances. The rev1 put the > camera on i2c1 GPIOs 2&3, with the rev2 on i2c0 with GPIOs 0&1. > > Whilst it would be nice to have support for all platforms, this > doesn't stop us moving the mux into bcm283x-rpi.dtsi at a later date > to add support for the other devices. > I'm happy enough having the first step of getting Pi4 working, with > others being done later. Thanks :-) I would also be happy for other boards to get I2C0 mux support later. > [1] https://linux-rpi-kernel.infradead.narkive.com/lmzYlT3c/rfc-arm-dts-add-i2cmux-pinctrl-config-to-raspberry-pi-i2c-0 > > > Add a pinctrl-based I2C bus multiplexer to bcm2711-rpi.dtsi to model > > this multiplexing. The two child buses are named i2c0_0 and i2c0_1. > > > > Note that if you modified the dts before to add devices to the i2c bus > > appearing on pins gpio0 + gpio1 (either directly in the dts or using an > > overlay), you have to put these into the i2c0_0 node introduced here > > now. > > > > Signed-off-by: Uwe Kleine-König <uwe@xxxxxxxxxxxxxxxxx> > > Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > > --- > > Changes since v3: > > > > - Split addition of the RTC to a separate patch > > - Move the mux to bcm2711-rpi.dtsi > > --- > > arch/arm/boot/dts/broadcom/bcm2711-rpi.dtsi | 31 +++++++++++++++++++++ > > 1 file changed, 31 insertions(+) > > > > diff --git a/arch/arm/boot/dts/broadcom/bcm2711-rpi.dtsi b/arch/arm/boot/dts/broadcom/bcm2711-rpi.dtsi > > index 86188eabeb24..826ed6efa9ff 100644 > > --- a/arch/arm/boot/dts/broadcom/bcm2711-rpi.dtsi > > +++ b/arch/arm/boot/dts/broadcom/bcm2711-rpi.dtsi > > @@ -17,6 +17,32 @@ aliases { > > pcie0 = &pcie0; > > blconfig = &blconfig; > > }; > > + > > + i2c0mux: i2c0mux { > > + compatible = "i2c-mux-pinctrl"; > > + #address-cells = <1>; > > + #size-cells = <0>; > > + > > + i2c-parent = <&i2c0>; > > + > > + pinctrl-names = "i2c0", "i2c0-vc"; > > + pinctrl-0 = <&i2c0_gpio0>; > > + pinctrl-1 = <&i2c0_gpio44>; > > + > > + status = "disabled"; > > Why defaulting to disabled? > > The current mainline DT defaults to i2c0 being enabled on GPIOs 0&1 > (done via bcm2835-rpi.dtsi). > If the mux is disabled, then this change has left i2c0 being enabled > but with no pinctrl property, so it's not connected to the outside > world. > GPIOs 44&45 have never had any other user, therefore claiming them for > the mux isn't a regression in my view. I don't recall why I disabled it. Your explanation makes sense, I'll drop the status property. > As long as we can enable the other platforms later, and with the minor > caveat over being enabled or not: > > Acked-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx> Thank you. I'll send a new version of the series soon, Florian wanted to pick the DT integration sooner than later. > Minor point that CONFIG_I2C_MUX_PINCTRL appears not to be in the arm64 > defconfig. I don't know what the policy is there, but there seem to be > many other SoCs throwing modules in there for their configurations. > It is in arm/multi_v7_defconfig. Good question. > > + > > + i2c0_0: i2c@0 { > > + reg = <0>; > > + #address-cells = <1>; > > + #size-cells = <0>; > > + }; > > + > > + i2c0_1: i2c@1 { > > + reg = <1>; > > + #address-cells = <1>; > > + #size-cells = <0>; > > + }; > > + }; > > }; > > > > &firmware { > > @@ -49,6 +75,11 @@ &hvs { > > clocks = <&firmware_clocks 4>; > > }; > > > > +&i2c0 { > > + /delete-property/ pinctrl-names; > > + /delete-property/ pinctrl-0; > > +}; > > + > > &rmem { > > /* > > * RPi4's co-processor will copy the board's bootloader configuration -- Regards, Laurent Pinchart
