linux-kernel - Re: [PATCH] HID: i2c-hid: Add 60ms delay after SET

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Message-Id: <869337EE-BA79-4C83-B7AA-9CA76885D5D3@canonical.com>
Date:   Tue, 11 Aug 2020 14:00:14 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Pavel Balan <admin@...ma.net>,
        Daniel Playfair Cal <daniel.playfair.cal@...il.com>,
        HungNien Chen <hn.chen@...dahitech.com>,
        You-Sheng Yang <vicamo.yang@...onical.com>,
        Aaron Ma <aaron.ma@...onical.com>,
        "open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] HID: i2c-hid: Add 60ms delay after SET_POWER ON

Hi Hans,

> On Aug 11, 2020, at 00:13, Hans de Goede <hdegoede@...hat.com> wrote:
> 
> Hi,
> 
> On 10-08-2020 16:29, Kai-Heng Feng wrote:
>> Goodix touchpad fails to operate in I2C mode after system suspend.
>> According to the vendor, Windows is more forgiving and there's a 60ms
>> delay after SET_POWER ON command.
>> So let's do the same here, to workaround for the touchpads that depend
>> on the delay.
>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> 
> Interesting I send a very similar patch a couple of days ago,
> after debugging some touchpads issues on a BMAX Y13 laptop:
> 
> https://patchwork.kernel.org/patch/11701541/
> 
> If you look at that patch you will see that if we add a
> sleep on power-on to i2c_hid_set_power(), we can remove
> an existing sleep after power-on from i2c_hid_hwreset().
> 
> And there is an interesting comment there which should
> probably be moved (as my patch does) and corrected for the
> new knowledge so that people reading the code in the future
> now why the sleep is there.

Thanks for the info.
Can you please update your patch with 60ms to supersede mine?

> 
> Other then that we've come to the same conclusion, but
> your sleep is much longer. I guess that is ok though,
> are you sure we need 60ms as a minimum?
> Is that what goodix
> said?

Yes, I was told by Goodix that the 60ms delay is needed.

Kai-Heng

> 
> Regards,
> 
> Hans
> 
> 
>> ---
>>  drivers/hid/i2c-hid/i2c-hid-core.c | 3 +++
>>  1 file changed, 3 insertions(+)
>> diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
>> index 294c84e136d7..7b24a27fad95 100644
>> --- a/drivers/hid/i2c-hid/i2c-hid-core.c
>> +++ b/drivers/hid/i2c-hid/i2c-hid-core.c
>> @@ -419,6 +419,9 @@ static int i2c_hid_set_power(struct i2c_client *client, int power_state)
>>  	if (ret)
>>  		dev_err(&client->dev, "failed to change power setting.\n");
>>  +	if (!ret && power_state == I2C_HID_PWR_ON)
>> +		msleep(60);
>> +
>>  set_pwr_exit:
>>  	return ret;
>>  }
>