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Date:   Sat, 02 Jan 2021 12:19:38 +0000
From:   Barnabás Pőcze <pobrn@...tonmail.com>
To:     Jiaxun Yang <jiaxun.yang@...goat.com>
Cc:     "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Ike Panhc <ike.pan@...onical.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <mgross@...ux.intel.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] platform/x86: ideapad-laptop: Add has_touchpad_switch

2021. január 2., szombat 3:36 keltezéssel, Jiaxun Yang írta:

> 在 2021/1/2 上午1:09, Barnabás Pőcze 写道:
> > Hi
> >
> >
> > 2021. január 1., péntek 17:08 keltezéssel, Jiaxun Yang írta:
> >
> >> [...]
> >>>> @@ -1006,6 +1018,10 @@ static int ideapad_acpi_add(struct platform_device *pdev)
> >>>>   	if (!priv->has_hw_rfkill_switch)
> >>>>   		write_ec_cmd(priv->adev->handle, VPCCMD_W_RF, 1);
> >>>>
> >>>> +	/* The same for Touchpad */
> >>>> +	if (!priv->has_touchpad_switch)
> >>>> +		write_ec_cmd(priv->adev->handle, VPCCMD_W_TOUCHPAD, 1);
> >>>> +
> >>> Shouldn't it be the other way around: `if (priv->has_touchpad_switch)`?
> >> It is to prevent accidentally disable touchpad on machines that do have EC switch,
> >> so it's intentional.
> >> [...]
> > Sorry, but the explanation not fully clear to me. The commit message seems to
> > indicate that some models "do not use EC to switch touchpad", and I take that
> > means that reading from VPCCMD_R_TOUCHPAD will not reflect the actual state of the
> > touchpad and writing to VPCCMD_W_TOUCHPAD will not change the state of the touchpad.
>
> I'm just trying to prevent removing functionality on machines that
> touchpad can be controlled
> by EC but also equipped I2C HID touchpad. At least users will have a
> functional touchpad
> after that.
>

Thanks for the clarification.


> >
> > But then why do you still write to VPCCMD_W_TOUCHPAD on devices where supposedly
> > this does not have any effect (at least not the desired one)? And the part of the
> > code I made my comment about only runs on machines on which the touchpad supposedly
> > cannot be controlled by the EC. What am I missing?
> >
> > And there is the other problem: on some machines, this patch removes working
> > functionality.
> Yeah that's a problem. I just don't want to repeat the story of rfkill
> whitelist, it ends up with
> countless machine to be added.
>
> Maybe I should specify HID of touchpad as well. Two machines that known
> to be problematic
> all have ELAN0634 touchpad.

I think that would be better since the Lenovo Yoga 520-14IKB 80X8 device
I'm concerned about has a SYNA2B2C touchpad device, so at least that wouldn't be
affected.


Regards,
Barnabás Pőcze

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