linux-kernel - Re: [PATCH v10 05/12] Input: wacom_i2c

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Message-ID: <YS1DGuTTAEKAd2Yr@google.com>
Date:   Mon, 30 Aug 2021 13:44:10 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Alistair Francis <alistair@...stair23.me>, ping.cheng@...om.com,
        tatsunosuke.tobita@...om.com
Cc:     linux-input@...r.kernel.org, linux-imx@....com,
        kernel@...gutronix.de, pinglinux@...il.com, junkpainting@...il.com,
        linux-kernel@...r.kernel.org, alistair23@...il.com,
        robh+dt@...nel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v10 05/12] Input: wacom_i2c - Read the descriptor values

On Sun, Aug 29, 2021 at 07:19:18PM +1000, Alistair Francis wrote:
> When we query the device let's also read the descriptor from the device.
> This tells us useful information, including the version, which we use to
> determine a generation.
> 
> This is based on the driver from Wacom.
> 
> Signed-off-by: Alistair Francis <alistair@...stair23.me>
> ---
>  drivers/input/touchscreen/wacom_i2c.c | 64 +++++++++++++++++++++++++++
>  1 file changed, 64 insertions(+)
> 
> diff --git a/drivers/input/touchscreen/wacom_i2c.c b/drivers/input/touchscreen/wacom_i2c.c
> index 28255c77d426..72ba4a36459b 100644
> --- a/drivers/input/touchscreen/wacom_i2c.c
> +++ b/drivers/input/touchscreen/wacom_i2c.c
> @@ -16,6 +16,7 @@
>  #include <linux/of.h>
>  #include <asm/unaligned.h>
>  
> +#define WACOM_DESC_REG	0x01
>  #define WACOM_CMD_QUERY0	0x04
>  #define WACOM_CMD_QUERY1	0x00
>  #define WACOM_CMD_QUERY2	0x33
> @@ -24,11 +25,46 @@
>  #define WACOM_CMD_THROW1	0x00
>  #define WACOM_QUERY_SIZE	19
>  
> +#define WACOM_MAX_DATA_SIZE_BG9     10
> +#define WACOM_MAX_DATA_SIZE_G12     15
> +#define WACOM_MAX_DATA_SIZE_AG14    17
> +#define WACOM_MAX_DATA_SIZE         22
> +
> +/* Generation selction */
> +/* Before and at G9 generation */
> +#define WACOM_BG9	0
> +/* G12 generation the IC supports "height"*/
> +#define WACOM_G12	1
> +/* After and at G14 generation the IC supports "height" and
> + * it is defined as "Z" axis
> + */
> +#define WACOM_AG14	2
> +
> +struct wacom_desc {
> +	u16 descLen;
> +	u16 version;
> +	u16 reportLen;
> +	u16 reportReg;
> +	u16 inputReg;
> +	u16 maxInputLen;
> +	u16 outputReg;
> +	u16 maxOutputLen;
> +	u16 commReg;
> +	u16 dataReg;
> +	u16 vendorID;
> +	u16 productID;
> +	u16 fwVersion;
> +	u16 misc_high;
> +	u16 misc_low;
> +};

This looks like I2C HID descriptor. Is the device actually I2C HID
compatible? If so we should use that and abandon this driver.

Ping, Tatsunosuke, please advise.

Thanks.

-- 
Dmitry