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Date:   Tue, 18 Dec 2018 18:13:43 +1000
From:   Peter Hutterer <peter.hutterer@who-t.net>
To:     Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@gmail.com>, kt.liao@emc.com.tw,
        Aaron Ma <aaron.ma@canonical.com>,
        Kai Heng Feng <kai.heng.feng@canonical.com>,
        linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org
Subject: Re: [PATCH] Input: elantech - Disable elan-i2c for P52 and P72
Message-ID: <20181218081343.GA4701@jelly>
References: <20181212154205.24025-1-benjamin.tissoires@redhat.com>
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On Wed, Dec 12, 2018 at 04:42:05PM +0100, Benjamin Tissoires wrote:
> The current implementation of elan_i2c is known to not support those
> 2 laptops.
> 
> A proper fix is to tweak both elantech and elan_i2c to transmit the
> correct information from PS/2, which would make a bad candidate for
> stable.
> 
> So to give us some time for fixing the root of the problem, disable
> elan_i2c for the devices we know are not behaving properly.
> 
> Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1803600
> Link: https://bugs.archlinux.org/task/59714
> Fixes: df077237cf55 Input: elantech - detect new ICs and setup Host Notify for them
> 
> Cc: stable@vger.kernel.org  # v4.18+
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

Acked-by: Peter Hutterer <peter.hutterer@who-t.net>

Cheers,
   Peter

> ---
>  drivers/input/mouse/elantech.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
> index 2d95e8d93cc7..830ae9f07045 100644
> --- a/drivers/input/mouse/elantech.c
> +++ b/drivers/input/mouse/elantech.c
> @@ -1767,6 +1767,18 @@ static int elantech_smbus = IS_ENABLED(CONFIG_MOUSE_ELAN_I2C_SMBUS) ?
>  module_param_named(elantech_smbus, elantech_smbus, int, 0644);
>  MODULE_PARM_DESC(elantech_smbus, "Use a secondary bus for the Elantech device.");
>  
> +static const char * const i2c_blacklist_pnp_ids[] = {
> +	/*
> +	 * these are known to not be working properly as bits are missing
> +	 * in elan_i2c
> +	 */
> +	"LEN2131", /* ThinkPad P52 w/ NFC */
> +	"LEN2132", /* ThinkPad P52 */
> +	"LEN2133", /* ThinkPad P72 w/ NFC */
> +	"LEN2134", /* ThinkPad P72 */
> +	NULL
> +};
> +
>  static int elantech_create_smbus(struct psmouse *psmouse,
>  				 struct elantech_device_info *info,
>  				 bool leave_breadcrumbs)
> @@ -1802,10 +1814,12 @@ static int elantech_setup_smbus(struct psmouse *psmouse,
>  
>  	if (elantech_smbus == ELANTECH_SMBUS_NOT_SET) {
>  		/*
> -		 * New ICs are enabled by default.
> +		 * New ICs are enabled by default, unless mentioned in
> +		 * i2c_blacklist_pnp_ids.
>  		 * Old ICs are up to the user to decide.
>  		 */
> -		if (!ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version))
> +		if (!ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version) ||
> +		    psmouse_matches_pnp_id(psmouse, i2c_blacklist_pnp_ids))
>  			return -ENXIO;
>  	}
>  
> -- 
> 2.19.2
>