linux-kernel - Re: [PATCH 03/10] arm64: dts: imx8mp-skov: use I2C5 for DDC

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Message-ID: <d4728cc0-8f1b-4c0a-8133-527d68643d26@pengutronix.de>
Date: Mon, 6 Jan 2025 16:27:41 +0100
From: Ahmad Fatoum <a.fatoum@...gutronix.de>
To: Frank Li <Frank.li@....com>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
 Sascha Hauer <s.hauer@...gutronix.de>,
 Pengutronix Kernel Team <kernel@...gutronix.de>,
 Fabio Estevam <festevam@...il.com>, Oleksij Rempel
 <o.rempel@...gutronix.de>, devicetree@...r.kernel.org, imx@...ts.linux.dev,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/10] arm64: dts: imx8mp-skov: use I2C5 for DDC

On 19.12.24 20:27, Frank Li wrote:
> On Thu, Dec 19, 2024 at 06:43:56PM +0100, Ahmad Fatoum wrote:
>> Hello Frank,
>>
>> On 19.12.24 18:34, Frank Li wrote:
>>> On Thu, Dec 19, 2024 at 08:25:27AM +0100, Ahmad Fatoum wrote:
>>>> The HDMI DDC pads can be muxed either to an i.MX I2C controller or
>>>> to a limited I2C controller within the Designware HDMI bridge.
>>>>
>>>> So far we muxed the pads to the HDMI bridge, but the i.MX I2C controller
>>>> is the better choice:
>>>
>>> Switch to the i.MX I2C controller because
>>>
>>>>
>>>>   - We use DDC/CI commands for display brightness configuration, but the
>>>>     Linux driver refuses[1] transfers to/from address 0x37, because the
>>>>     controller doesn't support multi-byte requests.
>>>
>>>       Designware HDMI Limited I2C controller doesn't support multi-byte
>>> requests and display brightness configuration by DDC/CI command need it.
>>>
>>>>
>>>>   - The driver doesn't support I2C bus recovery, but we need that,
>>>>     because some HDMI panels used with the board can be flaky.
>>>
>>>       Designware HDMI Limited I2C controller doesn't support I2C bus
>>> recovery.
>>>
>>>>
>>>> As the i.MX I2C controller doesn't have either of these limitations,
>>>> let's make use of it instead.
>>>
>>> Reduntant. can be removed.
>>
>> Sorry, I am very much open to review feedback, but I fail to see how
>> your subjective take improves things.
> 
> Ref https://docs.kernel.org/process/submitting-patches.html
> 
> "Describe your changes in imperative mood, e.g. “make xyzzy do frotz”
> instead of “[This patch] makes xyzzy do frotz” or “[I] changed xyzzy to do
> frotz”, as if you are giving orders to the codebase to change its behaviour."
> 
> Avoid use "we(same as "I" in above example) ..."

We is replaced by passive voice in v2.

Cheers,
Ahmad

> 
> Frank
> 
>>
>> Thanks,
>> Ahmad
>>
>>
>>
>>
>>>
>>> Frank
>>>>
>>>> [1]: https://lore.kernel.org/all/20190722181945.244395-1-mka@chromium.org/
>>>>
>>>> Signed-off-by: Ahmad Fatoum <a.fatoum@...gutronix.de>
>>>> ---
>>>>  .../boot/dts/freescale/imx8mp-skov-revb-hdmi.dts   | 26 ++++++++++++++++++++--
>>>>  1 file changed, 24 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/freescale/imx8mp-skov-revb-hdmi.dts b/arch/arm64/boot/dts/freescale/imx8mp-skov-revb-hdmi.dts
>>>> index c1ca69da3cb8..206116be8166 100644
>>>> --- a/arch/arm64/boot/dts/freescale/imx8mp-skov-revb-hdmi.dts
>>>> +++ b/arch/arm64/boot/dts/freescale/imx8mp-skov-revb-hdmi.dts
>>>> @@ -9,12 +9,34 @@ / {
>>>>  	compatible = "skov,imx8mp-skov-revb-hdmi", "fsl,imx8mp";
>>>>  };
>>>>
>>>> +&i2c5 {
>>>> +	pinctrl-names = "default", "gpio";
>>>> +	pinctrl-0 = <&pinctrl_i2c5>;
>>>> +	pinctrl-1 = <&pinctrl_i2c5_gpio>;
>>>> +	scl-gpios = <&gpio3 26 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
>>>> +	sda-gpios = <&gpio3 27 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
>>>> +	clock-frequency = <100000>;
>>>> +	status = "okay";
>>>> +};
>>>> +
>>>>  &iomuxc {
>>>>  	pinctrl_hdmi: hdmigrp {
>>>>  		fsl,pins = <
>>>> -			MX8MP_IOMUXC_HDMI_DDC_SCL__HDMIMIX_HDMI_SCL		0x1c3
>>>> -			MX8MP_IOMUXC_HDMI_DDC_SDA__HDMIMIX_HDMI_SDA		0x1c3
>>>>  			MX8MP_IOMUXC_HDMI_HPD__HDMIMIX_HDMI_HPD			0x19
>>>>  		>;
>>>>  	};
>>>> +
>>>> +	pinctrl_i2c5: i2c5grp {
>>>> +		fsl,pins = <
>>>> +			MX8MP_IOMUXC_HDMI_DDC_SCL__I2C5_SCL			0x400001c2
>>>> +			MX8MP_IOMUXC_HDMI_DDC_SDA__I2C5_SDA			0x400001c2
>>>> +		>;
>>>> +	};
>>>> +
>>>> +	pinctrl_i2c5_gpio: i2c5gpiogrp {
>>>> +		fsl,pins = <
>>>> +			MX8MP_IOMUXC_HDMI_DDC_SCL__GPIO3_IO26			0x400001c2
>>>> +			MX8MP_IOMUXC_HDMI_DDC_SDA__GPIO3_IO27			0x400001c2
>>>> +		>;
>>>> +	};
>>>>  };
>>>>
>>>> --
>>>> 2.39.5
>>>>
>>>
>>
>>
>> --
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> 


-- 
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