From: Tomasz Kramkowski tk@the-tk.com
[ Upstream commit c3883fe06488a483658ba5d849b70e49bee15e7c ]
This patch fixes an issue in drivers/hid/hid-input.c where values outside of the logical range are not clamped when "null state" bit of the input control is not set.
This was discussed on the lists [1] and this change stems from the fact due to the ambiguity of the HID specification it might be appropriate to follow Microsoft's own interpretation of the specification. As noted in Microsoft's documentation [2] in the section titled "Required HID usages for digitizers" it is noted that values reported outside the logical range "will be considered as invalid data and the value will be changed to the nearest boundary value (logical min/max)."
This patch fixes an issue where the (1292:4745) Innomedia INNEX GENESIS/ATARI reports out of range values for its X and Y axis of the DPad which, due to the null state bit being unset, are forwarded to userspace as is. Now these values will get clamped to the logical range before being forwarded to userspace. This device was also used to test this patch.
This patch expands on commit 3f3752705dbd ("HID: reject input outside logical range only if null state is set").
[1]: http://lkml.kernel.org/r/20170307131036.GA853@gaia.local [2]: https://msdn.microsoft.com/en-us/library/windows/hardware/dn672278(v=vs.85)....
Signed-off-by: Tomasz Kramkowski tk@the-tk.com Acked-by: Benjamin Tissoires benjamin.tissoires@redhat.com Signed-off-by: Jiri Kosina jkosina@suse.cz Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- drivers/hid/hid-input.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c index 33d3deb32888..53e54855c366 100644 --- a/drivers/hid/hid-input.c +++ b/drivers/hid/hid-input.c @@ -1128,19 +1128,26 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct
/* * Ignore out-of-range values as per HID specification, - * section 5.10 and 6.2.25. + * section 5.10 and 6.2.25, when NULL state bit is present. + * When it's not, clamp the value to match Microsoft's input + * driver as mentioned in "Required HID usages for digitizers": + * https://msdn.microsoft.com/en-us/library/windows/hardware/dn672278(v=vs.85).... * * The logical_minimum < logical_maximum check is done so that we * don't unintentionally discard values sent by devices which * don't specify logical min and max. */ if ((field->flags & HID_MAIN_ITEM_VARIABLE) && - (field->flags & HID_MAIN_ITEM_NULL_STATE) && - (field->logical_minimum < field->logical_maximum) && - (value < field->logical_minimum || - value > field->logical_maximum)) { - dbg_hid("Ignoring out-of-range value %x\n", value); - return; + (field->logical_minimum < field->logical_maximum)) { + if (field->flags & HID_MAIN_ITEM_NULL_STATE && + (value < field->logical_minimum || + value > field->logical_maximum)) { + dbg_hid("Ignoring out-of-range value %x\n", value); + return; + } + value = clamp(value, + field->logical_minimum, + field->logical_maximum); }
/*