linux-kernel - RE: [PATCH] HID: i2c-hid: Add I2C_HID_QUIRK_NO_DELAY_AFTER_PWR

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Date:   Tue, 18 May 2021 09:07:53 +0800
From:   "Johnny.Chuang" <johnny.chuang@....com.tw>
To:     "'Harry Cutts'" <hcutts@...omium.org>,
        "'Johnny Chuang'" <johnny.chuang.emc@...il.com>
Cc:     "'Dmitry Torokhov'" <dmitry.torokhov@...il.com>,
        "'Benjamin Tissoires'" <benjamin.tissoires@...hat.com>,
        "'Peter Hutterer'" <peter.hutterer@...-t.net>,
        "'lkml'" <linux-kernel@...r.kernel.org>,
        "'linux-input'" <linux-input@...r.kernel.org>,
        "'James Chen'" <james.chen@....com.tw>,
        "'Jennifer Tsai'" <jennifer.tsai@....com.tw>,
        "'Paul Liang'" <paul.liang@....com.tw>,
        "'Jeff Chuang'" <jeff.chuang@....com.tw>,
        "'Douglas Anderson'" <dianders@...omium.org>,
        "'Jingle'" <jingle.wu@....com.tw>, "'Paris Yeh'" <pyeh@...gle.com>,
        "'sukumar . ghorai'" <sukumar.ghorai@...el.corp-partner.google.com>
Subject: RE: [PATCH] HID: i2c-hid: Add I2C_HID_QUIRK_NO_DELAY_AFTER_PWR_ON to optimize timing

> On Mon, 17 May 2021 at 16:57, Johnny Chuang
> <johnny.chuang.emc@...il.com> wrote:
> >
> > There is a hard coding 60ms delay after I2C_HID_PWR_ON commadn.
> > Elan didn't need the delay, so we add a quirk to reduce boot time and
> resume time.
> >
> > Optimized: eef4016243e9("HID: i2c-hid: Always sleep 60ms after
> > I2C_HID_PWR_ON commands")
> 
> I don't think Optimized: is a valid commit tag, though I'm not sure if it'll cause
> any problems.

I will change to Fixed tag at PATCH v2.

> 
> >
> > Signed-off-by: Johnny Chuang <johnny.chuang.emc@...il.com>
> > ---
> >  drivers/hid/i2c-hid/i2c-hid-core.c | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c
> > b/drivers/hid/i2c-hid/i2c-hid-core.c
> > index 9993133..e7ec280 100644
> > --- a/drivers/hid/i2c-hid/i2c-hid-core.c
> > +++ b/drivers/hid/i2c-hid/i2c-hid-core.c
> > [...snip...]
> > @@ -178,6 +179,11 @@ static const struct i2c_hid_quirks {
> >                  I2C_HID_QUIRK_RESET_ON_RESUME },
> >         { USB_VENDOR_ID_ITE,
> I2C_DEVICE_ID_ITE_LENOVO_LEGION_Y720,
> >                 I2C_HID_QUIRK_BAD_INPUT_SIZE },
> > +       /*
> > +        * Optimize boot time and resume time
> > +        */
> 
> This comment is a bit too vague to be useful; maybe state that Elan devices
> don't need the delay instead, or just remove the comment.
> 
> Other than that,

Okay, I will change to Elan devices don't need the delay at PATCH v2.

> 
> Reviewed-by: Harry Cutts <hcutts@...omium.org>
> 
> > +       { USB_VENDOR_ID_ELAN, HID_ANY_ID,
> > +                I2C_HID_QUIRK_NO_DELAY_AFTER_PWR_ON },
> >         { 0, 0 }
> >  };
> >
> > @@ -427,7 +433,8 @@ static int i2c_hid_set_power(struct i2c_client *client,
> int power_state)
> >          * PWR_ON requests. Testing has confirmed that several devices
> >          * will not work properly without a delay after a PWR_ON
> request.
> >          */
> > -       if (!ret && power_state == I2C_HID_PWR_ON)
> > +       if (!ret && power_state == I2C_HID_PWR_ON &&
> > +           !(ihid->quirks &
> I2C_HID_QUIRK_NO_DELAY_AFTER_PWR_ON))
> >                 msleep(60);
> >
> >         return ret;
> > --
> > 2.7.4
> >