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From:   Benjamin Tissoires <benjamin.tissoires@redhat.com>
Date:   Wed, 21 Sep 2022 14:35:09 +0200
Message-ID: <CAO-hwJ+gCVPv2zoQtyA-535sGDyvqNQ8gfmpySQGJnmUhmFyQg@mail.gmail.com>
Subject: Re: [PATCH v4] HID: nintendo: check analog user calibration for plausibility
To:     Johnothan King <johnothanking@protonmail.com>
Cc:     "Daniel J. Ogorchock" <djogorchock@gmail.com>,
        Jiri Kosina <jikos@kernel.org>,
        "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Wed, Sep 21, 2022 at 12:56 PM Johnothan King
<johnothanking@protonmail.com> wrote:
>
> Arne Wendt writes:
>   Cheap clone controllers may (falsely) report as having a user
>   calibration for the analog sticks in place, but return
>   wrong/impossible values for the actual calibration data.
>   In the present case at mine, the controller reports having a
>   user calibration in place and successfully executes the read
>   commands. The reported user calibration however is
>   min = center = max = 0.
>
>   This pull request addresses problems of this kind by checking the
>   provided user calibration-data for plausibility (min < center < max)
>   and falling back to the default values if implausible.
>
> I'll note that I was experiencing a crash because of this bug when using
> the GuliKit KingKong 2 controller. The crash manifests as a divide by
> zero error in the kernel logs:
> kernel: divide error: 0000 [#1] PREEMPT SMP NOPTI
>
> Link: https://github.com/nicman23/dkms-hid-nintendo/pull/25
> Link: https://github.com/DanielOgorchock/linux/issues/36
> Co-authored-by: Arne Wendt <arne.wendt@tuhh.de>
> Signed-off-by: Johnothan King <johnothanking@protonmail.com>
> ---

Thanks for the quick v4.

Daniel, I applied it without your rev-by. I think we are close enough
to what you reviewed previously. The only thing though is that I just
realized I lost your rev-by from v2. If you really want it, I can
probably force push the patch.

Anyway, applied to for-6.1/nintendo in hid.git.

Cheers,
Benjamin

> Changes in v2:
>  - Move the plausibility check to joycon_read_stick_calibration() and
>    have that function return -EINVAL if the check fails.
>  - In the plausibility check, change >= to ==. hid_field_extract() never
>    returns a negative value, so a scenario involving min > center or
>    center > max is impossible.
>  - To reduce code duplication, move the code for setting default
>    calibration values into a single function called
>    joycon_use_default_calibration().
>
> Changes in v3:
>  - Unbreak warning string to conform to coding style.
>  - Change joycon_use_default_calibration() to accept a struct hid_device
>    pointer instead of a struct joycon_ctlr pointer.
>
> Changes in v4:
>  - Reformat joycon_use_default_calibration() another time to move stick
>    and ret onto the same line.
>  - Revert == to >= change to account for rollover.
>  - Additional minor change to comment for value check.
>
>  drivers/hid/hid-nintendo.c | 55 +++++++++++++++++++++-----------------
>  1 file changed, 30 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
> index 5cb5a1d53b71..71e2a9a0882a 100644
> --- a/drivers/hid/hid-nintendo.c
> +++ b/drivers/hid/hid-nintendo.c
> @@ -760,12 +760,31 @@ static int joycon_read_stick_calibration(struct joycon_ctlr *ctlr, u16 cal_addr,
>         cal_y->max = cal_y->center + y_max_above;
>         cal_y->min = cal_y->center - y_min_below;
>
> -       return 0;
> +       /* check if calibration values are plausible */
> +       if (cal_x->min >= cal_x->center || cal_x->center >= cal_x->max ||
> +           cal_y->min >= cal_y->center || cal_y->center >= cal_y->max)
> +               ret = -EINVAL;
> +
> +       return ret;
>  }
>
>  static const u16 DFLT_STICK_CAL_CEN = 2000;
>  static const u16 DFLT_STICK_CAL_MAX = 3500;
>  static const u16 DFLT_STICK_CAL_MIN = 500;
> +static void joycon_use_default_calibration(struct hid_device *hdev,
> +                                          struct joycon_stick_cal *cal_x,
> +                                          struct joycon_stick_cal *cal_y,
> +                                          const char *stick, int ret)
> +{
> +       hid_warn(hdev,
> +                "Failed to read %s stick cal, using defaults; e=%d\n",
> +                stick, ret);
> +
> +       cal_x->center = cal_y->center = DFLT_STICK_CAL_CEN;
> +       cal_x->max = cal_y->max = DFLT_STICK_CAL_MAX;
> +       cal_x->min = cal_y->min = DFLT_STICK_CAL_MIN;
> +}
> +
>  static int joycon_request_calibration(struct joycon_ctlr *ctlr)
>  {
>         u16 left_stick_addr = JC_CAL_FCT_DATA_LEFT_ADDR;
> @@ -793,38 +812,24 @@ static int joycon_request_calibration(struct joycon_ctlr *ctlr)
>                                             &ctlr->left_stick_cal_x,
>                                             &ctlr->left_stick_cal_y,
>                                             true);
> -       if (ret) {
> -               hid_warn(ctlr->hdev,
> -                        "Failed to read left stick cal, using dflts; e=%d\n",
> -                        ret);
> -
> -               ctlr->left_stick_cal_x.center = DFLT_STICK_CAL_CEN;
> -               ctlr->left_stick_cal_x.max = DFLT_STICK_CAL_MAX;
> -               ctlr->left_stick_cal_x.min = DFLT_STICK_CAL_MIN;
>
> -               ctlr->left_stick_cal_y.center = DFLT_STICK_CAL_CEN;
> -               ctlr->left_stick_cal_y.max = DFLT_STICK_CAL_MAX;
> -               ctlr->left_stick_cal_y.min = DFLT_STICK_CAL_MIN;
> -       }
> +       if (ret)
> +               joycon_use_default_calibration(ctlr->hdev,
> +                                              &ctlr->left_stick_cal_x,
> +                                              &ctlr->left_stick_cal_y,
> +                                              "left", ret);
>
>         /* read the right stick calibration data */
>         ret = joycon_read_stick_calibration(ctlr, right_stick_addr,
>                                             &ctlr->right_stick_cal_x,
>                                             &ctlr->right_stick_cal_y,
>                                             false);
> -       if (ret) {
> -               hid_warn(ctlr->hdev,
> -                        "Failed to read right stick cal, using dflts; e=%d\n",
> -                        ret);
> -
> -               ctlr->right_stick_cal_x.center = DFLT_STICK_CAL_CEN;
> -               ctlr->right_stick_cal_x.max = DFLT_STICK_CAL_MAX;
> -               ctlr->right_stick_cal_x.min = DFLT_STICK_CAL_MIN;
>
> -               ctlr->right_stick_cal_y.center = DFLT_STICK_CAL_CEN;
> -               ctlr->right_stick_cal_y.max = DFLT_STICK_CAL_MAX;
> -               ctlr->right_stick_cal_y.min = DFLT_STICK_CAL_MIN;
> -       }
> +       if (ret)
> +               joycon_use_default_calibration(ctlr->hdev,
> +                                              &ctlr->right_stick_cal_x,
> +                                              &ctlr->right_stick_cal_y,
> +                                              "right", ret);
>
>         hid_dbg(ctlr->hdev, "calibration:\n"
>                             "l_x_c=%d l_x_max=%d l_x_min=%d\n"
> --
> 2.37.3
>
>