From: Jiri Kosina <jikos@kernel.org>
To: "Gerecke, Jason" <killertofu@gmail.com>
Cc: linux-input@vger.kernel.org,
Benjamin Tissoires <benjamin.tissoires@redhat.com>,
Ping Cheng <pinglinux@gmail.com>,
Aaron Armstrong Skomra <skomra@gmail.com>,
stable@vger.kernel.org, Jason Gerecke <jason.gerecke@wacom.com>,
Aaron Armstrong Skomra <aaron.skomra@wacom.com>
Subject: Re: [PATCH] HID: wacom: generic: Treat serial number and related fields as unsigned
Date: Wed, 6 Nov 2019 21:38:43 +0100 (CET) [thread overview]
Message-ID: <nycvar.YFH.7.76.1911062138270.1799@cbobk.fhfr.pm> (raw)
In-Reply-To: <20191106195946.552879-1-jason.gerecke@wacom.com>
On Wed, 6 Nov 2019, Gerecke, Jason wrote:
> From: Jason Gerecke <killertofu@gmail.com>
>
> The HID descriptors for most Wacom devices oddly declare the serial
> number and other related fields as signed integers. When these numbers
> are ingested by the HID subsystem, they are automatically sign-extended
> into 32-bit integers. We treat the fields as unsigned elsewhere in the
> kernel and userspace, however, so this sign-extension causes problems.
> In particular, the sign-extended tool ID sent to userspace as ABS_MISC
> does not properly match unsigned IDs used by xf86-input-wacom and libwacom.
>
> We introduce a function 'wacom_s32tou' that can undo the automatic sign
> extension performed by 'hid_snto32'. We call this function when processing
> the serial number and related fields to ensure that we are dealing with
> and reporting the unsigned form. We opt to use this method rather than
> adding a descriptor fixup in 'wacom_hid_usage_quirk' since it should be
> more robust in the face of future devices.
>
> Ref: https://github.com/linuxwacom/input-wacom/issues/134
> Fixes: f85c9dc678 ("HID: wacom: generic: Support tool ID and additional tool types")
> CC: <stable@vger.kernel.org> # v4.10+
> Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
> Reviewed-by: Aaron Armstrong Skomra <aaron.skomra@wacom.com>
Applied to for-5.4/upstream-fixes.
--
Jiri Kosina
SUSE Labs
prev parent reply other threads:[~2019-11-06 20:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-06 19:59 [PATCH] HID: wacom: generic: Treat serial number and related fields as unsigned Gerecke, Jason
2019-11-06 20:38 ` Jiri Kosina [this message]
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