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From:   Benjamin Tissoires <benjamin.tissoires@gmail.com>
Date:   Mon, 7 Jan 2019 08:58:46 +0100
Message-ID: <CAN+gG=HodVpN1YpXZ=zEXcFb1tMEgkVWLCOYbyLQ-8trqs699w@mail.gmail.com>
Subject: Re: [PATCH] Elantech Touchpad: Fix Elantech touchpad and trackpoint
 for Lenovo ThinkPad notebooks.
To:     Philipp Kaelin <kaelinphilipp@gmail.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        linux-input <linux-input@vger.kernel.org>,
        linux-kernel@vger.kernel.org
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Hi Philipp,

On Sat, Dec 29, 2018 at 6:35 AM Philipp Kaelin <kaelinphilipp@gmail.com> wrote:
>
> Initial situation:
> - The touchpad of a Lenovo ThinkPad L580 doesn't work with newer kernel versions eg. 4.20
> - It used to work on earlier versions eg. 4.14
>
> Cause:
> - The elantech driver was adapted in to support SMBus wich not all firmware versions
>   of the elantech firmware support. The SMBus is used as default.
>
> Solution:
> - Previously a blacklist was introduced for devices which doesn't support the access using SMBus.
>   The ThinkPad P52 and P72 have already been fixed by adding it to such a blacklist in a prevois patch.

nitpick: you are using "prevois" instead of "previous" :)

>   The exact same solution fixed also the issue on the mentioned ThinkPad L580.
>
> Change:
> 1) The firmware id of the ThinkPad L580 was added to this blacklist.
> 2) To not have a half baked solution the information which firmware versions are using the same driver
>    and therefore most probably have all the same issue was extracted from the Lenovo Windows driver package.
>    All these firmware versions are now also added to the blacklist.
>
> Risk assesment:
> As in prevois versions of the kernel eg. 4.14 none of the devices used to be accessed via SMBus
> (and they are reported to work at this time) it's quite safe that this blaklisting doesn't cause
> any harm on devices which have not been testes but included in the blacklist.
>
> Signed-off-by: Philipp Kaelin <kaelinphilipp@gmail.com>
> ---
>  drivers/input/mouse/elantech.c | 23 +++++++++++++++++++----
>  1 file changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
> index 9fe075c137dc..e5fa8cfd8393 100644
> --- a/drivers/input/mouse/elantech.c
> +++ b/drivers/input/mouse/elantech.c
> @@ -1772,10 +1772,25 @@ 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 */
> +       "LEN2131", /* Walter-3  w/ NFC          ThinkPad P52 w/ NFC     */
> +       "LEN2132", /* Walter-3  w/o/ NFC        ThinkPad P52            */
> +       "LEN2133", /* Chiron    w/ NFC          ThinkPad P72 w/ NFC     */
> +       "LEN2134", /* Chiron    w/o/ NFC        ThinkPad P72            */
> +       "LEN2037", /* Lando     w/ NFC          ThinkPad L580 w/ NFC    */
> +       "LEN2038", /* Lando     w/o/ NFC        ThinkPad L580           */
> +       "LEN004F", /* Storm     w/o/ NFC                                */
> +       "LEN005C", /* Storm     w/ NFC                                  */
> +       "LEN2030", /* Carling                                           */
> +       "LEN2031", /* Bell                                              */
> +       "LEN2032", /* Bell-2                                            */
> +       "LEN2033", /* Storm-2                                           */
> +       "LEN2034", /* Storm-3                                           */
> +       "LEN2035", /* Solo      w/ NFC                                  */
> +       "LEN2036", /* Solo      w/o/ NFC                                */
> +       "LEN2039", /* Leia                                              */
> +       "LEN2130", /* Kylo      (Clamshell)                             */
> +       "LEN008F", /* Kolar     w/o/ NF                                 */
> +       "LEN0090", /* Kolar     w/ NFC                                  */

That is quite a list. My initial idea with this blacklist was to keep
it short and fix the initial issue to be able to remove it entirely
(or at least on the devices we can test).
So 2 questions:
- do you have the commercial names of the various PNPId you are adding?
- are you able to test all of those? Especially if we get the SMBus
driver fixed?

I am fine adding the patch as a fix for 4.21 and backport this to
stable, but I still intend to fix elan_i2c for the next cycle (4.22)
so I'd like to know if we can safely test those machine later on.

Cheers,
Benjamin

>         NULL
>  };
>
> --
> 2.19.2
>