linux-kernel - Re: [PATCH v2] Input: elantech: Enable SMBus on new (2018+) systems

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Date:   Thu, 11 Apr 2019 15:54:35 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        廖崇榮 <kt.liao@....com.tw>,
        "open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] Input: elantech: Enable SMBus on new (2018+) systems


at 16:33, Benjamin Tissoires <benjamin.tissoires@...hat.com> wrote:

> On Mon, Jan 21, 2019 at 8:03 AM Kai-Heng Feng
> <kai.heng.feng@...onical.com> wrote:
>> There are some new HP laptops with Elantech touchpad don't support
>> multitouch.
>>
>> Currently we use ETP_NEW_IC_SMBUS_HOST_NOTIFY() to check if SMBus is
>> supported, but in addition to firmware version, the bus type also
>> informs us if the IC can support SMBus, so also check that.
>>
>> In case of breaking old ICs, only enables SMBus on systems manufactured
>> after 2018, alongsides aforementioned checks.
>>
>> Lastly, consolidats all check into elantech_use_host_notify() and use it
>> to determine whether to use PS/2 or SMBus.
>>
>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
>> ---
>> v2:
>> - Wording.
>> - Further restrain on older systems (< 2018).
>>
>>  drivers/input/mouse/elantech.c | 63 ++++++++++++++++++----------------
>>  1 file changed, 34 insertions(+), 29 deletions(-)
>>
>> diff --git a/drivers/input/mouse/elantech.c  
>> b/drivers/input/mouse/elantech.c
>> index 9fe075c137dc..2594130b0079 100644
>> --- a/drivers/input/mouse/elantech.c
>> +++ b/drivers/input/mouse/elantech.c
>> @@ -1799,6 +1799,39 @@ static int elantech_create_smbus(struct psmouse  
>> *psmouse,
>>                                   leave_breadcrumbs);
>>  }
>>
>> +static bool elantech_use_host_notify(struct psmouse *psmouse,
>> +                                    struct elantech_device_info *info)
>> +{
>> +       bool host_notify = false;
>> +
>> +       if (ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version))
>> +               host_notify = true;
>> +       else {
>> +               switch (info->bus) {
>> +               case ETP_BUS_PS2_ONLY:
>> +                       /* expected case */
>> +                       break;
>> +               case ETP_BUS_SMB_ALERT_ONLY:
>> +                       /* fall-through  */
>> +               case ETP_BUS_PS2_SMB_ALERT:
>> +                       psmouse_dbg(psmouse, "Ignoring SMBus provider  
>> through alert protocol.\n");
>> +                       break;
>> +               case ETP_BUS_SMB_HST_NTFY_ONLY:
>> +                       /* fall-through  */
>> +               case ETP_BUS_PS2_SMB_HST_NTFY:
>> +                       host_notify = true;
>> +                       break;
>> +               default:
>> +                       psmouse_dbg(psmouse,
>> +                                   "Ignoring SMBus bus provider %d.\n",
>> +                                   info->bus);
>> +               }
>> +       }
>> +
>> +       /* SMbus implementation is stable after 2018 */
>> +       return host_notify && (dmi_get_bios_year() >= 2018);
>
> Strictly speaking, the check for the year should be in the `switch
> (info->bus)`, but OTOH, laptops with ETP_NEW_IC_SMBUS_HOST_NOTIFY
> should be manufactured after 2018 too, so we should be good.
>
> Acked-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>

Hi Dmitry,

Would it be possible to include this patch?

Kai-Heng

>
> Cheers,
> Benjamin
>
>> +}
>> +
>>  /**
>>   * elantech_setup_smbus - called once the PS/2 devices are enumerated
>>   * and decides to instantiate a SMBus InterTouch device.
>> @@ -1818,7 +1851,7 @@ static int elantech_setup_smbus(struct psmouse  
>> *psmouse,
>>                  * i2c_blacklist_pnp_ids.
>>                  * Old ICs are up to the user to decide.
>>                  */
>> -               if (!ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version) ||
>> +               if (!elantech_use_host_notify(psmouse, info) ||
>>                     psmouse_matches_pnp_id(psmouse, i2c_blacklist_pnp_ids))
>>                         return -ENXIO;
>>         }
>> @@ -1838,34 +1871,6 @@ static int elantech_setup_smbus(struct psmouse  
>> *psmouse,
>>         return 0;
>>  }
>>
>> -static bool elantech_use_host_notify(struct psmouse *psmouse,
>> -                                    struct elantech_device_info *info)
>> -{
>> -       if (ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version))
>> -               return true;
>> -
>> -       switch (info->bus) {
>> -       case ETP_BUS_PS2_ONLY:
>> -               /* expected case */
>> -               break;
>> -       case ETP_BUS_SMB_ALERT_ONLY:
>> -               /* fall-through  */
>> -       case ETP_BUS_PS2_SMB_ALERT:
>> -               psmouse_dbg(psmouse, "Ignoring SMBus provider through  
>> alert protocol.\n");
>> -               break;
>> -       case ETP_BUS_SMB_HST_NTFY_ONLY:
>> -               /* fall-through  */
>> -       case ETP_BUS_PS2_SMB_HST_NTFY:
>> -               return true;
>> -       default:
>> -               psmouse_dbg(psmouse,
>> -                           "Ignoring SMBus bus provider %d.\n",
>> -                           info->bus);
>> -       }
>> -
>> -       return false;
>> -}
>> -
>>  int elantech_init_smbus(struct psmouse *psmouse)
>>  {
>>         struct elantech_device_info info;
>> —

>> 2.17.1