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Subject[PATCH] HID: nintendo: check analog user calibration for plausibility
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>
---
drivers/hid/hid-nintendo.c | 24 ++++++++++++++++++++++--
1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
index 6028af3c3aae..7f287f6a75f5 100644
--- a/drivers/hid/hid-nintendo.c
+++ b/drivers/hid/hid-nintendo.c
@@ -793,7 +793,17 @@ static int joycon_request_calibration(struct joycon_ctlr *ctlr)
&ctlr->left_stick_cal_x,
&ctlr->left_stick_cal_y,
true);
- if (ret) {
+
+ /*
+ * Check whether read succeeded and perform plausibility check
+ * for retrieved values.
+ */
+ if (ret ||
+ ctlr->left_stick_cal_x.min >= ctlr->left_stick_cal_x.center ||
+ ctlr->left_stick_cal_x.center >= ctlr->left_stick_cal_x.max ||
+ ctlr->left_stick_cal_y.min >= ctlr->left_stick_cal_y.center ||
+ ctlr->left_stick_cal_y.center >= ctlr->left_stick_cal_y.max
+ ) {
hid_warn(ctlr->hdev,
"Failed to read left stick cal, using dflts; e=%d\n",
ret);
@@ -812,7 +822,17 @@ static int joycon_request_calibration(struct joycon_ctlr *ctlr)
&ctlr->right_stick_cal_x,
&ctlr->right_stick_cal_y,
false);
- if (ret) {
+
+ /*
+ * Check whether read succeeded and perform plausibility check
+ * for retrieved values.
+ */
+ if (ret ||
+ ctlr->right_stick_cal_x.min >= ctlr->right_stick_cal_x.center ||
+ ctlr->right_stick_cal_x.center >= ctlr->right_stick_cal_x.max ||
+ ctlr->right_stick_cal_y.min >= ctlr->right_stick_cal_y.center ||
+ ctlr->right_stick_cal_y.center >= ctlr->right_stick_cal_y.max
+ ) {
hid_warn(ctlr->hdev,
"Failed to read right stick cal, using dflts; e=%d\n",
ret);
--
2.37.3

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