linux-kernel - Re: [PATCH v2] platform/x86: ideapad-laptop: Disable touchpad

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Date:   Mon, 7 Nov 2022 10:58:36 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Manyi Li <limanyi@...ontech.com>
Cc:     ike.pan@...onical.com, linux-kernel@...r.kernel.org,
        markgross@...nel.org, platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH v2] platform/x86: ideapad-laptop: Disable touchpad_switch

Hi Manyi,

On 10/18/22 11:53, Manyi Li wrote:
> Ideapads for "Lenovo Yoga 3 Pro 1370" and "ZhaoYang K4e-IML" do not
> use EC to switch touchpad.
> 
> Reading VPCCMD_R_TOUCHPAD will return zero thus touchpad may be blocked
> unexpectedly.
> 
> Signed-off-by: Manyi Li <limanyi@...ontech.com>

I have applied this patch for now, since it should be safe to do so
as the exceptions added are DMI string based.

But I would really like to see a better fix for this, by for example
checking if the touchpad is connected over I2C. Can you run
"acpidump -o acpidump.txt" and then send me a private email with the
generated acpidump.txt ?   Please do this for both models if possible.

Also I don't entirely understand why this patch is necessary in
the first place. You say that the touchpad is connected over I2C;
and when priv->features.touchpad_ctrl_via_ec = 1 the following
2 commands are possibly run by the driver:

i8042_command(&param, value ? I8042_CMD_AUX_ENABLE : I8042_CMD_AUX_DISABLE);

        if (!priv->features.touchpad_ctrl_via_ec)
                write_ec_cmd(priv->adev->handle, VPCCMD_W_TOUCHPAD, 1);

Note the second command actually gets enabled by this patch setting
priv->features.touchpad_ctrl_via_ec = 0.

What (undesirable) behavior are you seeing without this patch ?

And can you try a kernel without this patch and then comment
out the i8042_command() command and see if that helps ?

If that does not help, can you try removing the "if" part of:

        if (!priv->features.touchpad_ctrl_via_ec)
                write_ec_cmd(priv->adev->handle, VPCCMD_W_TOUCHPAD, 1);

So that the write_ec_cmd() happens unconditionally and see if that
helps ?

Regards,

Hans


> ---
>  drivers/platform/x86/ideapad-laptop.c | 25 ++++++++++++++++++++++++-
>  1 file changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/ideapad-laptop.c b/drivers/platform/x86/ideapad-laptop.c
> index abd0c81d62c4..33b3dfdd1b08 100644
> --- a/drivers/platform/x86/ideapad-laptop.c
> +++ b/drivers/platform/x86/ideapad-laptop.c
> @@ -1533,6 +1533,24 @@ static const struct dmi_system_id hw_rfkill_list[] = {
>  	{}
>  };
>  
> +static const struct dmi_system_id no_touchpad_switch_list[] = {
> +	{
> +	.ident = "Lenovo Yoga 3 Pro 1370",
> +	.matches = {
> +		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
> +		DMI_MATCH(DMI_PRODUCT_VERSION, "Lenovo YOGA 3"),
> +		},
> +	},
> +	{
> +	.ident = "ZhaoYang K4e-IML",
> +	.matches = {
> +		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
> +		DMI_MATCH(DMI_PRODUCT_VERSION, "ZhaoYang K4e-IML"),
> +		},
> +	},
> +	{}
> +};
> +
>  static void ideapad_check_features(struct ideapad_private *priv)
>  {
>  	acpi_handle handle = priv->adev->handle;
> @@ -1541,7 +1559,12 @@ static void ideapad_check_features(struct ideapad_private *priv)
>  	priv->features.hw_rfkill_switch = dmi_check_system(hw_rfkill_list);
>  
>  	/* Most ideapads with ELAN0634 touchpad don't use EC touchpad switch */
> -	priv->features.touchpad_ctrl_via_ec = !acpi_dev_present("ELAN0634", NULL, -1);
> +	if (acpi_dev_present("ELAN0634", NULL, -1))
> +		priv->features.touchpad_ctrl_via_ec = 0;
> +	else if (dmi_check_system(no_touchpad_switch_list))
> +		priv->features.touchpad_ctrl_via_ec = 0;
> +	else
> +		priv->features.touchpad_ctrl_via_ec = 1;
>  
>  	if (!read_ec_data(handle, VPCCMD_R_FAN, &val))
>  		priv->features.fan_mode = true;