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Date:   Mon, 14 Aug 2023 11:20:04 +0200 (CEST)
From:   Jiri Kosina <jikos@kernel.org>
To:     Illia Ostapyshyn <ostapyshyn@sra.uni-hannover.de>
cc:     Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        Nils Fuhler <nils@nilsfuhler.de>
Subject: Re: [PATCH RESEND] HID: input: Support devices sending Eraser without
 Invert
In-Reply-To: <20230613152559.108594-1-ostapyshyn@sra.uni-hannover.de>
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References: <20230613152559.108594-1-ostapyshyn@sra.uni-hannover.de>
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On Tue, 13 Jun 2023, Illia Ostapyshyn wrote:

> Some digitizers (notably XP-Pen Artist 24) do not report the Invert
> usage when erasing.  This causes the device to be permanently stuck with
> the BTN_TOOL_RUBBER tool after sending Eraser, as Invert is the only
> usage that can release the tool.  In this state, Touch and Inrange are
> no longer reported to userspace, rendering the pen unusable.
> 
> Prior to commit 87562fcd1342 ("HID: input: remove the need for
> HID_QUIRK_INVERT"), BTN_TOOL_RUBBER was never set and Eraser events were
> simply translated into BTN_TOUCH without causing an inconsistent state.
> 
> Introduce HID_QUIRK_NOINVERT for such digitizers and detect them during
> hidinput_configure_usage().  This quirk causes the tool to be released
> as soon as Eraser is reported as not set.  Set BTN_TOOL_RUBBER in
> input->keybit when mapping Eraser.
> 
> Fixes: 87562fcd1342 ("HID: input: remove the need for HID_QUIRK_INVERT")
> Co-developed-by: Nils Fuhler <nils@nilsfuhler.de>
> Signed-off-by: Nils Fuhler <nils@nilsfuhler.de>
> Signed-off-by: Illia Ostapyshyn <ostapyshyn@sra.uni-hannover.de>

Applied, thanks.

> ---
> We were wondering about the reason to keep quirk bits reserved for
> backward compatibility.  Is it because of dynamic quirks at module load
> time?  

Yes, that is indeed the case.

Thanks,

-- 
Jiri Kosina
SUSE Labs