On 08/07/2019 21:58, Peter Rosin wrote:

On 2019-07-08 13:08, Marc Gonzalez wrote:

quoted

PROBLEM #2

The tuner (si2157) is not on the i2c5 bus, instead it is on a private
i2c bus *behind* si2168, which routes requests to the proper client.
For the time being, I don't know how to model this relationship in DT.
(TODO: check i2c_slave_cb_t slave_cb in struct i2c_client)
I have initialized si2157 in the si2168 driver, but this doesn't feel
right. (Though it seems all(?) users pair 2168 with 2157.)

diff --git a/arch/arm64/boot/dts/qcom/apq8098-batfish.dts b/arch/arm64/boot/dts/qcom/apq8098-batfish.dts
index 29d59ecad138..9353e62375a7 100644
--- a/arch/arm64/boot/dts/qcom/apq8098-batfish.dts
+++ b/arch/arm64/boot/dts/qcom/apq8098-batfish.dts

@@ -30,6 +30,28 @@
 	status = "ok";
 };
 
+&blsp1_i2c5 {
+	status = "ok";
+	clock-frequency = <100000>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&i2c5_default>;
+
+	dvb_demod: si2168@64 {
+		compatible = "silabs,si2168";
+		reg = <0x64>;
+		reset-gpios = <&tlmm 84 GPIO_ACTIVE_LOW>;

In principle, I think you should be able to add something like this here:

		i2c-gate {
			#address-cells = <1>;
			#size-cells = <0>;

			tuner@60 {
				compatible = "silabs,si2157";
				reg = <0x60>;
				/* whatever else is needed */
			};
		};

But in practice, I don't know if the si2157 driver understands that or
if there is anything else that gets in the way. Totally untested...

The i2c-gate child node is examined when you call i2c_mux_add_adapter
if you have provided the correct struct device in the second argument
when you called i2c_mux_alloc (I think that is already the case). You
also need to set the I2C_MUX_GATE flag in the i2c_mux_alloc call, but
I do not see a problem with that since I think only one child adapter
is added. If it is a problem to add the I2C_MUX_GATE flag, then you
can just adjust the above i2c-gate node according to the bindings in
Documentation/devicetree/bindings/i2c/i2c-mux.txt. I.e. add this
instead of the above i2c-gate node:

		i2c-mux {
			#address-cells = <1>;
			#size-cells = <0>;

			i2c@0 {
	                        #address-cells = <1>;
        	                #size-cells = <0>;
                	        reg = <0>;

				tuner@60 {
					compatible = "silabs,si2157";
					reg = <0x60>;
					/* whatever else is needed */
				};
			};
		};

But it feels *right* to add the I2C_MUX_GATE flag, because a gate is
what you have. I think?

Thanks, Peter!

Your solution works great. It's refreshing to have stuff work
out-of-the-box!

Problem #2 is now taken care of. And Brad proposed an elegant
solution (IMO) for Problem #1.

I'll send an updated RFC v2 tomorrow. (My patch series is a
complete mess right now.)

Regards.

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