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From:   Harry Cutts <hcutts@chromium.org>
Date:   Mon, 17 May 2021 17:15:37 -0700
Message-ID: <CA+jURcv-o3g3C6zZhGio7KKtco-b+dGk+vm=3Nj8ps_-yMQRNA@mail.gmail.com>
Subject: Re: [PATCH] HID: i2c-hid: Add I2C_HID_QUIRK_NO_DELAY_AFTER_PWR_ON to
 optimize timing
To:     Johnny Chuang <johnny.chuang.emc@gmail.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        Peter Hutterer <peter.hutterer@who-t.net>,
        lkml <linux-kernel@vger.kernel.org>,
        linux-input <linux-input@vger.kernel.org>,
        Johnny Chuang <johnny.chuang@emc.com.tw>,
        James Chen <james.chen@emc.com.tw>,
        Jennifer Tsai <jennifer.tsai@emc.com.tw>,
        Paul Liang <paul.liang@emc.com.tw>,
        Jeff Chuang <jeff.chuang@emc.com.tw>,
        Douglas Anderson <dianders@chromium.org>,
        Jingle <jingle.wu@emc.com.tw>, Paris Yeh <pyeh@google.com>,
        "sukumar . ghorai" <sukumar.ghorai@intel.corp-partner.google.com>
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On Mon, 17 May 2021 at 16:57, Johnny Chuang <johnny.chuang.emc@gmail.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.

>
> Signed-off-by: Johnny Chuang <johnny.chuang.emc@gmail.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,

Reviewed-by: Harry Cutts <hcutts@chromium.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
>