linux-kernel - Re: [PATCH v2] Input: cros-ec-keyb: Only register keyboard if rows/columns exist

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Date:   Mon, 25 Apr 2022 14:17:25 -0700
From:   Guenter Roeck <groeck@...gle.com>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        patches@...ts.linux.dev, Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Hsin-Yi Wang <hsinyi@...omium.org>
Subject: Re: [PATCH v2] Input: cros-ec-keyb: Only register keyboard if
 rows/columns exist

On Mon, Apr 25, 2022 at 2:07 PM Stephen Boyd <swboyd@...omium.org> wrote:
>
> If the device is a detachable, we may still probe this device because
> there are some button switches, e.g. volume buttons and power buttons,
> registered by this driver. Let's allow the device node to be missing row
> and column device properties to indicate that the keyboard matrix
> shouldn't be registered. This removes an input device on Trogdor devices
> such as Wormdingler that don't have a matrix keyboard, but still have
> power and volume buttons. That helps userspace understand there isn't
> a keyboard present when the detachable keyboard is disconnected.
>
> Cc: Benson Leung <bleung@...omium.org>
> Cc: Guenter Roeck <groeck@...omium.org>
> Cc: Douglas Anderson <dianders@...omium.org>
> Cc: Hsin-Yi Wang <hsinyi@...omium.org>
> Signed-off-by: Stephen Boyd <swboyd@...omium.org>

Reviewed-by: Guenter Roeck <groeck@...omium.org>

> ---
>
> Changes from v1 (https://lore.kernel.org/r/20220413033334.1514008-1-swboyd@chromium.org):
>  * Use device_property_present
>
>  drivers/input/keyboard/cros_ec_keyb.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
> index 6534dfca60b4..ceb23e2e0d94 100644
> --- a/drivers/input/keyboard/cros_ec_keyb.c
> +++ b/drivers/input/keyboard/cros_ec_keyb.c
> @@ -537,6 +537,15 @@ static int cros_ec_keyb_register_matrix(struct cros_ec_keyb *ckdev)
>         u32 key_pos;
>         unsigned int row, col, scancode, n_physmap;
>
> +       /*
> +        * No rows and columns? There isn't a matrix but maybe there are
> +        * switches to register in cros_ec_keyb_register_bs() because this is a
> +        * detachable device.
> +        */
> +       if (!device_property_present(dev, "keypad,num-rows") &&
> +           !device_property_present(dev, "keypad,num-cols"))
> +               return 0;
> +
>         err = matrix_keypad_parse_properties(dev, &ckdev->rows, &ckdev->cols);
>         if (err)
>                 return err;
>
> base-commit: 3123109284176b1532874591f7c81f3837bbdc17
> --
> https://chromeos.dev
>