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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <b8c8b16a-4beb-dc97-caaa-8f4753b81ce7@redhat.com>
Date:   Tue, 11 Aug 2020 14:59:33 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Kai-Heng Feng <kai.heng.feng@...onical.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,

On 8/11/20 8:00 AM, Kai-Heng Feng wrote:
> 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?

Sure, done.

Regards,

Hans


> 
>>
>> 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;
>>>   }
>>
>