Re: [PATCH 2/3] Input: wacom_w8001 - assign distinct phys paths to pen and touch devices

[Jason Gerecke]

On Fri, Oct 9, 2026 at 12:28 PM Dmitry Torokhov
<dmitry.torokhov@xxxxxxxxx> wrote:
>
> Previously, both pen and touch input devices used the same phys path
> "%s/input0", which made it impossible for userspace or udev rules to
> distinguish the devices by physical topology.
>
> Assign distinct phys paths by introducing separate buffers pen_phys
> ("%s/input0") and touch_phys ("%s/input1") in struct w8001. Pass the
> corresponding phys path to w8001_allocate_device() during pen and touch
> setup, and drop the shared phys buffer from struct w8001.
>
> Fixes: e0361b70175f ("Input: wacom_w8001 - split the touch and pen devices into two devices")

Does this really deserve a "Fixes" tag? This does not seem to be as
much of a "bug" as it is a limitation. Userspace and udev rules are
(currently) able to reliably distinguish the devices by name.
Obviously that's not ideal, but I don't see much benefit to this patch
getting backported to the stable trees -- especially when /existing/
udev rules aren't necessarily going to know what to do with this new
"input1" phys.

> Assisted-by: LLM

Same Assisted-by comments from Patch 1/3 apply.

Jason (she/they)
---
Now instead of four in the eights place /
you’ve got three, ‘Cause you added one  /
(That is to say, eight) to the two,     /
But you can’t take seven from three,    /
So you look at the sixty-fours....


> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> ---
>  drivers/input/touchscreen/wacom_w8001.c | 17 +++++++++++------
>  1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/input/touchscreen/wacom_w8001.c b/drivers/input/touchscreen/wacom_w8001.c
> index 1c48e2775214..e967f2413706 100644
> --- a/drivers/input/touchscreen/wacom_w8001.c
> +++ b/drivers/input/touchscreen/wacom_w8001.c
> @@ -91,7 +91,8 @@ struct w8001 {
>         unsigned char response_type;
>         unsigned char response[W8001_MAX_LENGTH];
>         unsigned char data[W8001_MAX_LENGTH];
> -       char phys[W8001_MAX_PHYS];
> +       char pen_phys[W8001_MAX_PHYS];
> +       char touch_phys[W8001_MAX_PHYS];
>         int type;
>         unsigned int pktlen;
>         u16 max_touch_x;
> @@ -495,7 +496,8 @@ static bool w8001_detect_touch(struct w8001 *w8001,
>  }
>
>  static struct input_dev *w8001_allocate_device(struct w8001 *w8001,
> -                                              const char *name)
> +                                              const char *name,
> +                                              const char *phys)
>  {
>         struct input_dev *dev;
>
> @@ -504,7 +506,7 @@ static struct input_dev *w8001_allocate_device(struct w8001 *w8001,
>                 return NULL;
>
>         dev->name = name;
> -       dev->phys = w8001->phys;
> +       dev->phys = phys;
>         dev->id.bustype = BUS_RS232;
>         dev->id.product = w8001->id;
>         dev->id.vendor = 0x056a;
> @@ -529,8 +531,10 @@ static int w8001_setup_pen(struct w8001 *w8001, const char *basename,
>         int error;
>
>         snprintf(w8001->pen_name, sizeof(w8001->pen_name), "%s Pen", basename);
> +       snprintf(w8001->pen_phys, sizeof(w8001->pen_phys), "%s/input0",
> +                w8001->serio->phys);
>
> -       dev = w8001_allocate_device(w8001, w8001->pen_name);
> +       dev = w8001_allocate_device(w8001, w8001->pen_name, w8001->pen_phys);
>         if (!dev)
>                 return -ENOMEM;
>
> @@ -572,8 +576,10 @@ static int w8001_setup_touch(struct w8001 *w8001, const char *basename,
>         int error;
>
>         snprintf(w8001->touch_name, sizeof(w8001->touch_name), "%s Finger", basename);
> +       snprintf(w8001->touch_phys, sizeof(w8001->touch_phys), "%s/input1",
> +                w8001->serio->phys);
>
> -       dev = w8001_allocate_device(w8001, w8001->touch_name);
> +       dev = w8001_allocate_device(w8001, w8001->touch_name, w8001->touch_phys);
>         if (!dev)
>                 return -ENOMEM;
>
> @@ -669,7 +675,6 @@ static int w8001_connect(struct serio *serio, struct serio_driver *drv)
>         w8001->serio = serio;
>         mutex_init(&w8001->mutex);
>         init_completion(&w8001->cmd_done);
> -       snprintf(w8001->phys, sizeof(w8001->phys), "%s/input0", serio->phys);
>
>         serio_set_drvdata(serio, w8001);
>         err = serio_open(serio, drv);
> --
> 2.56.0.385.gd3acb90ef8-goog
>
>