linux-kernel - Re: [PATCH] HID: i2c-hid: call the hid driver's suspend and resume callbacks

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Date:	Thu, 17 Jul 2014 13:00:31 -0400
From:	Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:	Andrew Duggan <aduggan@...aptics.com>
Cc:	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	Jiri Kosina <jkosina@...e.cz>,
	Vincent Huang <vincent.huang@...synaptics.com>,
	Mika Westerberg <mika.westerberg@...el.com>
Subject: Re: [PATCH] HID: i2c-hid: call the hid driver's suspend and resume
 callbacks

On Jul 11 2014 or thereabouts, Andrew Duggan wrote:
> Currently, the i2c-hid driver does not call the suspend, resume, and
> reset_resume callbacks in the hid_driver struct when those events occur.
> This means that HID drivers for i2c-hid devices will not be able to execute
> commands which may be needed during suspend or resume. One example is when a
> touchpad using the hid-multitouch driver gets reset by i2c-hid coming out of
> resume. Since the reset_resume callback never gets called the device is never
> put back into the correct input mode. This patch calls the suspend and resume
> callbacks and tries to duplicate the functionality of the usb-hid driver.
> 
> Signed-off-by: Andrew Duggan <aduggan@...aptics.com>
> Signed-off-by: Vincent Huang <vincent.huang@...synaptics.com>
> ---
> Hi Benjamin,
> 
> This is the patch which Vincent and I came up with to fix the behavior which we were seeing with touchpads not being operational after resuming. We only use the reset_resume callback since i2c_hid_resume is always doing a hardware reset and it doesn't seem like there is a condition in which the standard resume callback would be appropriate. Also, is a full hardware reset always needed when resuming?

Hi Andrew,

well, the PM management of i2c_hid has been handled by Mika (in CC) and
I am unfortunately not able to have a strong opinion on this. I still
lack of hardware properly supporting the suspend/resume mechanism.

So, you are in charge of that. IIRC, nothing prevents from not calling
hw_reset, but I guess this was the safer implementation we could have.

Anyway, the patch looks good:
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>

Cheers,
Benjamin

> 
>  drivers/hid/i2c-hid/i2c-hid.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index 21aafc8..747d544 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -1054,21 +1054,29 @@ static int i2c_hid_remove(struct i2c_client *client)
>  static int i2c_hid_suspend(struct device *dev)
>  {
>  	struct i2c_client *client = to_i2c_client(dev);
> +	struct i2c_hid *ihid = i2c_get_clientdata(client);
> +	struct hid_device *hid = ihid->hid;
> +	int ret = 0;
>  
>  	disable_irq(client->irq);
>  	if (device_may_wakeup(&client->dev))
>  		enable_irq_wake(client->irq);
>  
> +	if (hid->driver && hid->driver->suspend)
> +		ret = hid->driver->suspend(hid, PMSG_SUSPEND);
> +
>  	/* Save some power */
>  	i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
>  
> -	return 0;
> +	return ret;
>  }
>  
>  static int i2c_hid_resume(struct device *dev)
>  {
>  	int ret;
>  	struct i2c_client *client = to_i2c_client(dev);
> +	struct i2c_hid *ihid = i2c_get_clientdata(client);
> +	struct hid_device *hid = ihid->hid;
>  
>  	enable_irq(client->irq);
>  	ret = i2c_hid_hwreset(client);
> @@ -1078,6 +1086,11 @@ static int i2c_hid_resume(struct device *dev)
>  	if (device_may_wakeup(&client->dev))
>  		disable_irq_wake(client->irq);
>  
> +	if (hid->driver && hid->driver->reset_resume) {
> +		ret = hid->driver->reset_resume(hid);
> +		return ret;
> +	}
> +
>  	return 0;
>  }
>  #endif
> -- 
> 1.9.1
> 
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