linux-kernel - Re: [PATCH 1/1] Input: elantech: Use SMBus based on bus info

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Message-Id: <0BD3A587-B7B6-4C99-8F87-187394FF6EFC@canonical.com>
Date:   Fri, 18 Jan 2019 00:14:45 +0800
From:   Kai Heng Feng <kai.heng.feng@...onical.com>
To:     Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.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 1/1] Input: elantech: Use SMBus based on bus info



> On Jan 17, 2019, at 10:42 PM, Benjamin Tissoires <benjamin.tissoires@...hat.com> wrote:
> 
> Hi Kai-Heng,
> 
> On Thu, Jan 17, 2019 at 10:30 AM Kai-Heng Feng
> <kai.heng.feng@...onical.com> wrote:
>> 
>> There are some new HP laptops with Elantech touchpad don't support
>> multitouch.
>> 
>> Both ETP_BUS_SMB_HST_NTFY_ONLY and ETP_BUS_PS2_SMB_HST_NTFY devices can
>> use SMBus to support 5 fingers touch, so we need to chech them too.
>> 
>> So use elantech_use_host_notify() to do a more thouroughly check.
>> 
>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
>> ---
>> drivers/input/mouse/elantech.c | 58 +++++++++++++++++-----------------
>> 1 file changed, 29 insertions(+), 29 deletions(-)
>> 
>> diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
>> index 9fe075c137dc..5bcf1c147eb1 100644
>> --- a/drivers/input/mouse/elantech.c
>> +++ b/drivers/input/mouse/elantech.c
>> @@ -1799,6 +1799,34 @@ static int elantech_create_smbus(struct psmouse *psmouse,
>>                                  leave_breadcrumbs);
>> }
>> 
>> +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;
>> +}
>> +
>> /**
>>  * elantech_setup_smbus - called once the PS/2 devices are enumerated
>>  * and decides to instantiate a SMBus InterTouch device.
>> @@ -1818,7 +1846,7 @@ 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) ||
> 
> That was my initial approach of the series, but I ended up being more
> conservative as this would flip all of the existing elantech SMBUS
> capable touchpads to use elan_i2c.
> And I didn't want to deal with 4/5 year old laptops that suddenly broke.
> 
> So I wonder if you can restrict this default change to the recent
> laptops (let's say 2018+). Maybe by looking at their FW version or
> something else in the DMI?

It was KT who told me that I should use ETP_BUS_PS2_SMB_HST_NTFY.

As for date, KT still knows better than me.

KT, 
Can you name a year which is safe enough to enable SMBus?

Kai-Heng

> 
> Cheers,
> Benjamin
> 
>>                    psmouse_matches_pnp_id(psmouse, i2c_blacklist_pnp_ids))
>>                        return -ENXIO;
>>        }
>> @@ -1838,34 +1866,6 @@ 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