RE: [PATCH v11 1/4] HID: wacom_sys: Add support for flipping the data values

["Tobita, Tatsunosuke" <tatsunosuke.tobita@wacom.com>]

Hi Dmitry,

>I am really confused about this distinction. Could you please elaborate why wacom driver only supports 0x056a (and, curiously, some Lenovo) devices.
We want 0x2d1F to work with ***ONLY*** with the generic HID driver because the every recent firmware is designed for that; no help is needed from other sides.
In contrast, the most of the devices is required help from other sides. Therefore, the devices with VID 0x2D1F devices are supposed to run alone and separated out from our brand shipped products. 
I don't know how much we can go further to tell you about this -because of our business, but 0x2D1F was obtained such purpose. Your understanding is much appreciated.

Thanks,

Tats

-----Original Message-----
From: Dmitry Torokhov <dmitry.torokhov@gmail.com> 
Sent: Tuesday, October 19, 2021 10:51 AM
To: Ping Cheng <pinglinux@gmail.com>
Cc: Alistair Francis <alistair@alistair23.me>; shawnguo@kernel.org; s.hauer@pengutronix.de; linux-imx@nxp.com; Jiri Kosina <jikos@kernel.org>; Benjamin Tissoires <benjamin.tissoires@redhat.com>; linux-input <linux-input@vger.kernel.org>; devicetree@vger.kernel.org; LKML <linux-kernel@vger.kernel.org>; linux-arm-kernel@lists.infradead.org; alistair23@gmail.com
Subject: Re: [PATCH v11 1/4] HID: wacom_sys: Add support for flipping the data values

[EXTERNAL]

Hi Ping,

On Mon, Oct 18, 2021 at 10:41:55AM -0700, Ping Cheng wrote:
> Hi Alistair,
>
> On Sat, Oct 9, 2021, 4:44 AM Alistair Francis <alistair@alistair23.me>
> wrote:
>
> > Add support to the Wacom HID device for flipping the values based on 
> > device tree settings. This allows us to support devices where the 
> > panel is installed in a different orientation, such as the reMarkable2.
> >
>
> This device was designed for hid-generic driver, if it's not driven by 
> wacom_i2c.c or an out of tree driver.
>
> wacom.ko doesn't support vid 0x2d1f devices.

I am really confused about this distinction. Could you please elaborate why wacom driver only supports 0x056a (and, curiously, some Lenovo) devices.

Thanks.


>
> Nacked-by: Ping Cheng <Ping.Cheng@wacom.com>
>
> Sorry about that,
> Ping
>
> Signed-off-by: Alistair Francis <alistair@alistair23.me>
> > ---
> >  .../bindings/input/hid-over-i2c.txt           | 20 ++++++
> >  drivers/hid/wacom_sys.c                       | 25 ++++++++
> >  drivers/hid/wacom_wac.c                       | 61 +++++++++++++++++++
> >  drivers/hid/wacom_wac.h                       | 13 ++++
> >  4 files changed, 119 insertions(+)
> >
> > diff --git 
> > a/Documentation/devicetree/bindings/input/hid-over-i2c.txt
> > b/Documentation/devicetree/bindings/input/hid-over-i2c.txt
> > index c76bafaf98d2..16ebd7c46049 100644
> > --- a/Documentation/devicetree/bindings/input/hid-over-i2c.txt
> > +++ b/Documentation/devicetree/bindings/input/hid-over-i2c.txt
> > @@ -33,6 +33,26 @@ device-specific compatible properties, which 
> > should be used in addition to the
> >  - post-power-on-delay-ms: time required by the device after 
> > enabling its regulators
> >    or powering it on, before it is ready for communication.
> >
> > +  flip-tilt-x:
> > +    type: boolean
> > +    description: Flip the tilt X values read from device
> > +
> > +  flip-tilt-y:
> > +    type: boolean
> > +    description: Flip the tilt Y values read from device

Do these really need to be controlled separately from the main touchcsreen orientation?

> > +
> > +  flip-pos-x:
> > +    type: boolean
> > +    description: Flip the X position values read from device
> > +
> > +  flip-pos-y:
> > +    type: boolean
> > +    description: Flip the Y position values read from device

We already have touchscreen-inverted-x/y defined in Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml,
why are they not sufficient?

> > +
> > +  flip-distance:
> > +    type: boolean
> > +    description: Flip the distance values read from device

I am still confused of the notion of flipped distance.

> > +
> >  Example:
> >
> >         i2c-hid-dev@2c {
> > diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c index 
> > 93f49b766376..47d9590b10bd 100644
> > --- a/drivers/hid/wacom_sys.c
> > +++ b/drivers/hid/wacom_sys.c
> > @@ -10,6 +10,7 @@
> >
> >  #include "wacom_wac.h"
> >  #include "wacom.h"
> > +#include <linux/of.h>
> >  #include <linux/input/mt.h>
> >
> >  #define WAC_MSG_RETRIES                5
> > @@ -2730,6 +2731,28 @@ static void wacom_mode_change_work(struct 
> > work_struct *work)
> >         return;
> >  }
> >
> > +static void wacom_of_read(struct hid_device *hdev, struct wacom_wac
> > *wacom_wac)
> > +{
> > +       if (IS_ENABLED(CONFIG_OF)) {
> > +               wacom_wac->flip_tilt_x =
> > of_property_read_bool(hdev->dev.parent->of_node,
> > +                                                       "flip-tilt-x");
> > +               wacom_wac->flip_tilt_y =
> > of_property_read_bool(hdev->dev.parent->of_node,
> > +                                                       "flip-tilt-y");
> > +               wacom_wac->flip_pos_x =
> > of_property_read_bool(hdev->dev.parent->of_node,
> > +                                                       "flip-pos-x");
> > +               wacom_wac->flip_pos_y =
> > of_property_read_bool(hdev->dev.parent->of_node,
> > +                                                       "flip-pos-y");
> > +               wacom_wac->flip_distance =
> > of_property_read_bool(hdev->dev.parent->of_node,
> > +                                                       "flip-distance");
> > +       } else {
> > +               wacom_wac->flip_tilt_x = false;
> > +               wacom_wac->flip_tilt_y = false;
> > +               wacom_wac->flip_pos_x = false;
> > +               wacom_wac->flip_pos_y = false;
> > +               wacom_wac->flip_distance = false;
> > +       }
> > +}
> > +
> >  static int wacom_probe(struct hid_device *hdev,
> >                 const struct hid_device_id *id)  { @@ -2797,6 
> > +2820,8 @@ static int wacom_probe(struct hid_device *hdev,
> >                                  error);
> >         }
> >
> > +       wacom_of_read(hdev, wacom_wac);
> > +
> >         wacom_wac->probe_complete = true;
> >         return 0;
> >  }
> > diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c index 
> > 33a6908995b1..c01f683e23fa 100644
> > --- a/drivers/hid/wacom_wac.c
> > +++ b/drivers/hid/wacom_wac.c
> > @@ -3261,6 +3261,63 @@ static int wacom_status_irq(struct wacom_wac 
> > *wacom_wac, size_t len)
> >         return 0;
> >  }
> >
> > +static int wacom_of_irq(struct wacom_wac *wacom_wac, size_t len) {
> > +       const struct wacom_features *features = &wacom_wac->features;
> > +       unsigned char *data = wacom_wac->data;
> > +       struct input_dev *input = wacom_wac->pen_input;
> > +       unsigned int x, y, pressure;
> > +       unsigned char tsw, f1, f2, ers;
> > +       short tilt_x, tilt_y, distance;
> > +
> > +       if (!IS_ENABLED(CONFIG_OF))
> > +               return 0;
> > +
> > +       tsw = data[1] & WACOM_TIP_SWITCH_bm;
> > +       ers = data[1] & WACOM_ERASER_bm;
> > +       f1 = data[1] & WACOM_BARREL_SWITCH_bm;
> > +       f2 = data[1] & WACOM_BARREL_SWITCH_2_bm;
> > +       x = le16_to_cpup((__le16 *)&data[2]);
> > +       y = le16_to_cpup((__le16 *)&data[4]);
> > +       pressure = le16_to_cpup((__le16 *)&data[6]);
> > +
> > +       /* Signed */
> > +       tilt_x = get_unaligned_le16(&data[9]);
> > +       tilt_y = get_unaligned_le16(&data[11]);
> > +
> > +       distance = get_unaligned_le16(&data[13]);

You are still parsing raw data. The point of HID is to provide common framework for scaling raw values.

Thanks.

--
Dmitry