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Date: Thu, 6 Jun 2024 14:23:24 -0700
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Alistair Francis <alistair@alistair23.me>
Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
	alistair23@gmail.com
Subject: Re: [PATCH v2] Input: wacom_i2c - Clean up the query device fields
Message-ID: <ZmIozAu-R1nbRYHF@google.com>
References: <20211118123545.102872-1-alistair@alistair23.me>
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In-Reply-To: <20211118123545.102872-1-alistair@alistair23.me>

Hi Alistair,

On Thu, Nov 18, 2021 at 10:35:45PM +1000, Alistair Francis wrote:
> Improve the query device fields to be more verbose.
> 
> Signed-off-by: Alistair Francis <alistair@alistair23.me>

Could you please list what has changed since v1?

> ---
>  drivers/input/touchscreen/wacom_i2c.c | 45 ++++++++++++++++-----------
>  1 file changed, 27 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/wacom_i2c.c b/drivers/input/touchscreen/wacom_i2c.c
> index fe4ea6204a4e..50d159919bd1 100644
> --- a/drivers/input/touchscreen/wacom_i2c.c
> +++ b/drivers/input/touchscreen/wacom_i2c.c
> @@ -23,13 +23,20 @@
>  #define WACOM_BARREL_SWITCH_2	BIT(4)
>  #define WACOM_IN_PROXIMITY	BIT(5)
>  
> -/* Registers */
> -#define WACOM_CMD_QUERY0	0x04
> -#define WACOM_CMD_QUERY1	0x00
> -#define WACOM_CMD_QUERY2	0x33
> -#define WACOM_CMD_QUERY3	0x02
> -#define WACOM_CMD_THROW0	0x05
> -#define WACOM_CMD_THROW1	0x00
> +// Registers

I am partial to C-style comments, let's keep them.

> +#define WACOM_COMMAND_LSB	0x04
> +#define WACOM_COMMAND_MSB	0x00
> +
> +#define WACOM_DATA_LSB		0x05
> +#define WACOM_DATA_MSB		0x00
> +
> +// Report types
> +#define REPORT_FEATURE		0x30
> +
> +// Requests / operations
> +#define OPCODE_GET_REPORT	0x02
> +
> +#define WACOM_QUERY_REPORT	3
>  #define WACOM_QUERY_SIZE	19
>  
>  struct wacom_features {
> @@ -51,22 +58,24 @@ static int wacom_query_device(struct i2c_client *client,
>  			      struct wacom_features *features)
>  {
>  	int ret;
> -	u8 cmd1[] = { WACOM_CMD_QUERY0, WACOM_CMD_QUERY1,
> -			WACOM_CMD_QUERY2, WACOM_CMD_QUERY3 };
> -	u8 cmd2[] = { WACOM_CMD_THROW0, WACOM_CMD_THROW1 };
>  	u8 data[WACOM_QUERY_SIZE];
> +
> +	u8 get_query_data_cmd[] = {
> +		WACOM_COMMAND_LSB,
> +		WACOM_COMMAND_MSB,
> +		REPORT_FEATURE | WACOM_QUERY_REPORT,
> +		OPCODE_GET_REPORT,
> +		WACOM_DATA_LSB,
> +		WACOM_DATA_MSB,
> +	};
> +
>  	struct i2c_msg msgs[] = {
> +		// Request reading of feature ReportID: 3 (Pen Query Data)
>  		{
>  			.addr = client->addr,
>  			.flags = 0,
> -			.len = sizeof(cmd1),
> -			.buf = cmd1,
> -		},
> -		{
> -			.addr = client->addr,
> -			.flags = 0,
> -			.len = sizeof(cmd2),
> -			.buf = cmd2,
> +			.len = sizeof(get_query_data_cmd),
> +			.buf = get_query_data_cmd,

This combines writes into one message. Is this safe and works for all
devices? At the very least this needs to be mentioned in the patch
description.


>  		},
>  		{
>  			.addr = client->addr,
> -- 
> 2.31.1
> 

Thanks.

-- 
Dmitry