linux-kernel - Re: [PATCH 1/2] dt-bindings: input: document Novatek NVT touchscreen controller

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Date: Thu, 23 May 2024 05:11:21 -0500
From: Joel Selvaraj <joelselvaraj.oss@...il.com>
To: Hans de Goede <hdegoede@...hat.com>, Krzysztof Kozlowski
 <krzk@...nel.org>, Dmitry Torokhov <dmitry.torokhov@...il.com>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>
Cc: linux-input@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: input: document Novatek NVT touchscreen
 controller

Hi Hans de Goede

On 5/22/24 11:00, Hans de Goede wrote:
>>> +
>>> +properties:
>>> +  compatible:
>>> +    enum:
>>> +      - novatek,nvt-ts
>>
>> That's too generic. Looking at your driver change, it is not even needed.
> 
> I wrote the novatek-nvt-ts driver for an Acer Iconia One 7 B1-750 tablet,
> this is a x86 tablet which ships with Android as factory OS and because
> Android OS images use kernels where everything is hardcoded the ACPI tables
> do not describe this touchscreen. Instead the i2c_client for the touchscreen
> is manually instantiated by some x86 platform glue code. Since it is
> manually instantiated it uses i2c_device_id binding rather then OF/ACPI.
> 
> The generic "NVT-ts" i2c_device_id comes from me not knowing the controller
> panel type back then. In the mean time I have learned that the B1-750 uses
> NVT-NT11205 controller.
> 
> So what I think needs to happen here is add a preparation patch as first
> patch to this series which basically does this:
> 
> diff --git a/drivers/input/touchscreen/novatek-nvt-ts.c b/drivers/input/touchscreen/novatek-nvt-ts.c
> index 1a797e410a3f..224fd112b25a 100644
> --- a/drivers/input/touchscreen/novatek-nvt-ts.c
> +++ b/drivers/input/touchscreen/novatek-nvt-ts.c
> @@ -278,7 +278,7 @@ static int nvt_ts_probe(struct i2c_client *client)
>   }
>   
>   static const struct i2c_device_id nvt_ts_i2c_id[] = {
> -	{ "NVT-ts" },
> +	{ "NT11205-ts" },
>   	{ }
>   };
>   MODULE_DEVICE_TABLE(i2c, nvt_ts_i2c_id);
> diff --git a/drivers/platform/x86/x86-android-tablets/other.c b/drivers/platform/x86/x86-android-tablets/other.c
> index eb0e55c69dfe..5ecee6e66fb4 100644
> --- a/drivers/platform/x86/x86-android-tablets/other.c
> +++ b/drivers/platform/x86/x86-android-tablets/other.c
> @@ -40,7 +40,7 @@ static const struct x86_i2c_client_info acer_b1_750_i2c_clients[] __initconst =
>   	{
>   		/* Novatek NVT-ts touchscreen */
>   		.board_info = {
> -			.type = "NVT-ts",
> +			.type = "NT11205-ts",
>   			.addr = 0x34,
>   			.dev_name = "NVT-ts",
>   		},
> 
> This solves the too-generic ID problema nd can then be merged
> together with the rest of the series through the input tree.
> I'll give my ack as drivers/platform/x86 subsys maintainer for
> merging the x86-android-tablets change this way.

Ok, will do so in v2. Thanks.

> 
>>> +      - novatek,nt36672a-ts
>>
>> Eh, we have already panel. Why there is a need for touchscreen binding
>> (binding, not driver)?
> 
> I believe that the nt36672a identifier is an identifier for
> a novatek display assembly which contains both a DSI display
> panel as well as an I2C touchscreen. Since I2C devices need

Yeah.

> to be children of the I2C controller we need a separate node
> in the device tree for the I2c touchscreen-controller and since
> it is a separate node it needs it own compatible I believe ? >
> Regards,
> 
> Hans
> 

Regards,
Joel Selvaraj