linux-kernel - Re: [PATCH v5 1/2] ARM: dts: imx6: Add support for Toradex Apalis iMX6Q/D SoM

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Date:   Mon, 29 Aug 2016 13:54:50 -0700
From:   Stefan Agner <stefan@...er.ch>
To:     Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
Cc:     Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        linux-arm-kernel@...ts.infradead.org,
        Lucas Stach <l.stach@...gutronix.de>,
        Russell King <linux@....linux.org.uk>,
        Sascha Hauer <kernel@...gutronix.de>,
        Petr Štetiar <ynezz@...e.cz>,
        Fabio Estevam <festevam@...il.com>,
        Kumar Gala <galak@...eaurora.org>,
        Ian Campbell <ijc+devicetree@...lion.org.uk>,
        Joshua Clayton <stillcompiling@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Pawel Moll <pawel.moll@....com>,
        Mark Rutland <mark.rutland@....com>,
        Shawn Guo <shawnguo@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/2] ARM: dts: imx6: Add support for Toradex Apalis
 iMX6Q/D SoM

On 2016-08-29 06:28, Vladimir Zapolskiy wrote:
> Hi Marcel,
> 
> On 02/05/2016 06:12 PM, Marcel Ziswiler wrote:
>> From: Petr Štetiar <ynezz@...e.cz>
>>
>> Signed-off-by: Marcel Ziswiler <marcel.ziswiler@...adex.com>
>> Signed-off-by: Petr Štetiar <ynezz@...e.cz>
>> Reviewed-by: Stefan Agner <stefan@...er.ch>
>> ---
>>
> 
> because the change is in mainline now below is kind of out of date
> information, but you may find it helpful.
> 
> [snip]
> 
>> - fixed HDMI DDC (requires GPIO-based bitbanging I2C to be enabled)
> 
> This is not needed.
> 
> [snip]
> 
>> +	/* DDC_I2C: I2C2_SDA/SCL on MXM3 205/207 */
>> +	i2cddc: i2c@0 {
>> +		compatible = "i2c-gpio";
>> +		pinctrl-names = "default";
>> +		pinctrl-0 = <&pinctrl_i2c_ddc>;
>> +		gpios = <&gpio3 16 GPIO_ACTIVE_HIGH /* sda */
>> +			 &gpio2 30 GPIO_ACTIVE_HIGH /* scl */
>> +			>;
>> +		i2c-gpio,delay-us = <2>;	/* ~100 kHz */
>> +		status = "disabled";
>> +	};
>> +
> 
> This is not needed.
> 
> [snip]
> 
>> +	pinctrl_i2c_ddc: gpioi2cddcgrp {
>> +		fsl,pins = <
>> +			/* DDC bitbang */
>> +			MX6QDL_PAD_EIM_EB2__GPIO2_IO30 0x1b0b0
>> +			MX6QDL_PAD_EIM_D16__GPIO3_IO16 0x1b0b0
>> +		>;
>> +	};
>> +
> 
> Practically you don't need this overcomplicated GPIO-based bitbanging
> to emulate I2C, because the DW HDMI controller has a reduced I2C
> controller on board, you may take a look at its support published here:
> 
>    http://www.spinics.net/lists/dri-devel/msg116308.html
> 
> To utilize it the pads should be set to HDMI function instead of
> I2C or GPIO.

Thanks for the notification! I guess we'd also have to remove...

+&hdmi {
+    ddc-i2c-bus = <&i2cddc>;

...this line...

+    status = "okay";
+};
+
+&i2cddc {
+    status = "okay";
+};

and this from arch/arm/boot/dts/imx6q-apalis-ixora.dts.

--
Stefan