linux-kernel - Re: [PATCH] arm64: dts: meson-a1: add I2C nodes

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Date:   Tue, 10 Dec 2019 10:15:45 -0800
From:   Kevin Hilman <khilman@...libre.com>
To:     Jian Hu <jian.hu@...ogic.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Neil Armstrong <narmstrong@...libre.com>
Cc:     Rob Herring <robh@...nel.org>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Michael Turquette <mturquette@...libre.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Mark Rutland <mark.rutland@....com>,
        Jianxin Pan <jianxin.pan@...ogic.com>,
        linux-amlogic@...ts.infradead.org, linux-i2c@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: meson-a1: add I2C nodes

Jian Hu <jian.hu@...ogic.com> writes:

> Hi Kevin
>
> Thanks for your review
>
> On 2019/12/10 6:54, Kevin Hilman wrote:
>> Hi Jian,
>> 
>> Jian Hu <jian.hu@...ogic.com> writes:
>> 
>>> There are four I2C controllers in A1 series,
>>> Share the same comptible with AXG.The I2C nodes
>>> depend on pinmux and clock controller.
>>>
>>> Signed-off-by: Jian Hu <jian.hu@...ogic.com>
>>> ---
>>>   arch/arm64/boot/dts/amlogic/meson-a1.dtsi | 149 ++++++++++++++++++++++
>>>   1 file changed, 149 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/amlogic/meson-a1.dtsi b/arch/arm64/boot/dts/amlogic/meson-a1.dtsi
>>> index eab2ecd36aa8..d0a73d953f5e 100644
>>> --- a/arch/arm64/boot/dts/amlogic/meson-a1.dtsi
>>> +++ b/arch/arm64/boot/dts/amlogic/meson-a1.dtsi
>>> @@ -16,6 +16,13 @@
>>>   	#address-cells = <2>;
>>>   	#size-cells = <2>;
>>>   
>>> +	aliases {
>>> +		i2c0 = &i2c0;
>>> +		i2c1 = &i2c1;
>>> +		i2c2 = &i2c2;
>>> +		i2c3 = &i2c3;
>>> +	};
>>> +
>>>   	cpus {
>>>   		#address-cells = <2>;
>>>   		#size-cells = <0>;
>>> @@ -117,6 +124,46 @@
>>>   				};
>>>   			};
>>>   
>>> +			i2c0: i2c@...0 {
>>> +				compatible = "amlogic,meson-axg-i2c";
>>> +				reg = <0x0 0x1400 0x0 0x24>;
>> 
>> The AXG DT files use 0x20 for the length.  You are using 0x24.  I don't
>> see any additional registers added to the driver, so this doesn't look right.
> In fact, For G12 series and A1, the length should be 0x24. A new 
> register is added, And it is for IRQ handler timeout. If the 
> transmission is exceeding a limited time, it will abort the 
> transmission.Now the function is not used, There is completion to deal 
> the timeout in the driver. I will set the length 0x20 becouse of the new 
> register is not used.

Yes, we can extend it to 0x24 when support for the new register is
added, because that will mean adding a new compatible string also.

>> 
>>> +				interrupts = <GIC_SPI 32 IRQ_TYPE_EDGE_RISING>;
>>> +				#address-cells = <1>;
>>> +				#size-cells = <0>;
>>> +				clocks = <&clkc_periphs CLKID_I2C_M_A>;
>>> +				status = "disabled";
>>> +			};
>>> +
>>> +			i2c1: i2c@...0 {
>>> +				compatible = "amlogic,meson-axg-i2c";
>>> +				reg = <0x0 0x5c00 0x0 0x24>;
>>> +				interrupts = <GIC_SPI 68 IRQ_TYPE_EDGE_RISING>;
>>> +				#address-cells = <1>;
>>> +				#size-cells = <0>;
>>> +				clocks = <&clkc_periphs CLKID_I2C_M_B>;
>>> +				status = "disabled";
>>> +			};
>>> +
>>> +			i2c2: i2c@...0 {
>>> +				compatible = "amlogic,meson-axg-i2c";
>>> +				reg = <0x0 0x6800 0x0 0x24>;
>>> +				interrupts = <GIC_SPI 76 IRQ_TYPE_EDGE_RISING>;
>>> +				#address-cells = <1>;
>>> +				#size-cells = <0>;
>>> +				clocks = <&clkc_periphs CLKID_I2C_M_C>;
>>> +				status = "disabled";
>>> +			};
>>> +
>>> +			i2c3: i2c@...0 {
>>> +				compatible = "amlogic,meson-axg-i2c";
>>> +				reg = <0x0 0x6c00 0x0 0x24>;
>>> +				interrupts = <GIC_SPI 78 IRQ_TYPE_EDGE_RISING>;
>>> +				#address-cells = <1>;
>>> +				#size-cells = <0>;
>>> +				clocks = <&clkc_periphs CLKID_I2C_M_D>;
>>> +				status = "disabled";
>>> +			};
>>> +
>>>   			uart_AO: serial@...0 {
>>>   				compatible = "amlogic,meson-gx-uart",
>>>   					     "amlogic,meson-ao-uart";
>>> @@ -171,3 +218,105 @@
>>>   		#clock-cells = <0>;
>>>   	};
>>>   };
>>> +
>>> +&periphs_pinctrl {
>>> +	i2c0_f11_pins:i2c0-f11 {
>>> +		mux {
>>> +			groups = "i2c0_sck_f11",
>>> +				"i2c0_sda_f12";
>>> +			function = "i2c0";
>>> +			bias-pull-up;
>>> +			drive-strength-microamp = <3000>;
>> 
>> Can you also add some comment to the changelog about the need for
>> drive-strength compared to AXG.
>
> OK, Drive strength function is added for GPIO pins from G12 series.
> So does A1 series.

Yes, that's what I assumed.  Please add that to the changelog as one of
the new features in A1 compared to AXG.

Thanks,

Kevin