Re: Wrongly bound Elantech touchpad on Lenovo Yoga Slim 7

[Benjamin Tissoires]

Hi,

[adding Dmitry, the maintainer of the input tree and Hans, a colleague of mine]

On Fri, Feb 4, 2022 at 5:57 PM Takashi Iwai <tiwai@xxxxxxx> wrote:
>
> Hi,
>
> we've got a bug report on openSUSE Bugzilla about the broken touchpad
> on Lenovo Yoga Slim 7:
>   https://bugzilla.opensuse.org/show_bug.cgi?id=1193064
>
> The touchpad is an Elantech one, connected over i2c, and there are two
> drivers supporting it.  Unfortunately, the default one the system
> binds, elan-i2c input driver, doesn't seem working properly, while
> i2c-hid driver works.

Hans, we do have a similar bug on RHEL at
https://bugzilla.redhat.com/show_bug.cgi?id=2029078 (sorry, private
bug).

IIRC you worked on the discrimination between i2c-hid and elan_i2c (I
might be completely wrong though).
Would this patch be OK with you?

Cheers,
Benjamin

>
> I'm not sure what's the best fix for this, but below a quick
> workaround using a deny list with DMI matching.
> If this is OK, I can resubmit the patch for merging.
>
> Any comments appreciated.
>
>
> thanks,
>
> Takashi
>
> -- 8< --
> From: Takashi Iwai <tiwai@xxxxxxx>
> Subject: [PATCH] Input: elan_i2c: Add deny list for Lenovo Yoga Slim 7
>
> The touchpad on Lenovo Yoga Slim 7 doesn't work well with elan-i2c but
> rather better with i2c-hid.  Add a deny list for avoiding to bind with
> elan-i2c.
>
> BugLink: https://bugzilla.opensuse.org/show_bug.cgi?id=1193064
> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
> ---
>  drivers/input/mouse/elan_i2c_core.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/drivers/input/mouse/elan_i2c_core.c b/drivers/input/mouse/elan_i2c_core.c
> index 47af62c12267..fd08481f7aea 100644
> --- a/drivers/input/mouse/elan_i2c_core.c
> +++ b/drivers/input/mouse/elan_i2c_core.c
> @@ -18,6 +18,7 @@
>  #include <linux/acpi.h>
>  #include <linux/delay.h>
>  #include <linux/device.h>
> +#include <linux/dmi.h>
>  #include <linux/firmware.h>
>  #include <linux/i2c.h>
>  #include <linux/init.h>
> @@ -1222,6 +1223,20 @@ static void elan_disable_regulator(void *_data)
>         regulator_disable(data->vcc);
>  }
>
> +static const struct dmi_system_id elan_i2c_denylist[] __initconst = {
> +#if IS_ENABLED(CONFIG_I2C_HID_ACPI)
> +       {
> +               /* Lenovo Yoga Slim 7 is better supported by i2c-hid */
> +               .matches = {
> +                       DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
> +                       DMI_MATCH(DMI_PRODUCT_NAME, "82A3"),
> +                       DMI_MATCH(DMI_PRODUCT_VERSION, "Yoga Slim 7 14ITL05"),
> +               },
> +       },
> +#endif
> +       { }
> +};
> +
>  static int elan_probe(struct i2c_client *client,
>                       const struct i2c_device_id *dev_id)
>  {
> @@ -1233,6 +1248,10 @@ static int elan_probe(struct i2c_client *client,
>
>         if (IS_ENABLED(CONFIG_MOUSE_ELAN_I2C_I2C) &&
>             i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> +               if (dmi_check_system(elan_i2c_denylist)) {
> +                       dev_info(dev, "Hits deny list, skipping\n");
> +                       return -ENODEV;
> +               }
>                 transport_ops = &elan_i2c_ops;
>         } else if (IS_ENABLED(CONFIG_MOUSE_ELAN_I2C_SMBUS) &&
>                    i2c_check_functionality(client->adapter,
> --
> 2.31.1
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