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Date:   Wed, 04 Oct 2023 12:01:27 -0700
From:   Rain <rain@sunshowers.io>
To:     "Rahul Rameshbabu" <sergeantsagara@protonmail.com>,
        "Jiri Kosina" <jikos@kernel.org>,
        "Benjamin Tissoires" <benjamin.tissoires@redhat.com>,
        "Henrik Rydberg" <rydberg@bitmath.org>
Cc:     linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] HID: multitouch: Add required quirk for Synaptics 0xcd7e device
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On Sun, Sep 17, 2023, at 09:18, Rahul Rameshbabu wrote:
> Register the Synaptics device as a special multitouch device with certain
> quirks that may improve usability of the touchpad device.
>
> Reported-by: Rain <rain@sunshowers.io>
> Closes: 
> https://lore.kernel.org/linux-input/2bbb8e1d-1793-4df1-810f-cb0137341ff4@app.fastmail.com/
> Signed-off-by: Rahul Rameshbabu <sergeantsagara@protonmail.com>
> ---
>
> Notes:
>     Theory:
>    
>       I think the Synaptics device in the related email to the linux-input
>       mailing list requires certain quirks like MT_QUIRK_HOVERING to correctly
>       reconfigure the distance configuration for multitouch events. This might
>       explain why light touches were not registered originally when
>       MT_CLS_DEFAULT was used by default for the device. Would like to have
>       this patch tested before being merged. A Tested-by: git trailer can then
>       be appended.
>
>  drivers/hid/hid-multitouch.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 521b2ffb4244..8db4ae05febc 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -2144,6 +2144,10 @@ static const struct hid_device_id mt_devices[] = {
>  			USB_DEVICE_ID_MTP_STM)},
> 
>  	/* Synaptics devices */
> +	{ .driver_data = MT_CLS_WIN_8_FORCE_MULTI_INPUT,
> +		HID_DEVICE(BUS_I2C, HID_GROUP_MULTITOUCH_WIN_8,
> +			USB_VENDOR_ID_SYNAPTICS, 0xcd7e) },

Thanks for the patch! I haven't tested it yet but it looks promising.

The vendor ID isn't USB_VENDOR_ID_SYNAPTICS (0x06cb),
however -- it's SYNA7DB5 (0x7db5) which I guess is an alternative vendor
ID for Synaptics. Would be worth fixing that.

> +
>  	{ .driver_data = MT_CLS_WIN_8_FORCE_MULTI_INPUT,
>  		HID_DEVICE(BUS_I2C, HID_GROUP_MULTITOUCH_WIN_8,
>  			USB_VENDOR_ID_SYNAPTICS, 0xce08) },
> -- 
> 2.40.1

-- 
Rain
(they/she)