linux-kernel - Re: [PATCH v11 4/8] Input: goodix

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Date:	Thu, 19 Nov 2015 14:31:07 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	"Rafael J. Wysocki" <rafael@...nel.org>
Cc:	Irina Tirdea <irina.tirdea@...el.com>,
	Bastien Nocera <hadess@...ess.net>,
	Aleksei Mamlin <mamlinav@...il.com>,
	Karsten Merker <merker@...ian.org>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	Mark Rutland <mark.rutland@....com>,
	Rob Herring <robh+dt@...nel.org>,
	Octavian Purdila <octavian.purdila@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH v11 4/8] Input: goodix - add power management support

On Thu, Nov 19, 2015 at 2:18 PM, Rafael J. Wysocki <rafael@...nel.org> wrote:
> Hi,
>
> On Thu, Nov 19, 2015 at 7:24 PM, Dmitry Torokhov
> <dmitry.torokhov@...il.com> wrote:
>> On Thu, Nov 19, 2015 at 02:26:37PM +0200, Irina Tirdea wrote:
>>> Implement suspend/resume for goodix driver.
>>>
>
> [cut]
>
>>>
>>> +static int __maybe_unused goodix_suspend(struct device *dev)
>>> +{
>>> +     struct i2c_client *client = to_i2c_client(dev);
>>> +     struct goodix_ts_data *ts = i2c_get_clientdata(client);
>>> +     int error;
>>> +
>>> +     /* We need gpio pins to suspend/resume */
>>> +     if (!ts->gpiod_int || !ts->gpiod_rst)
>>> +             return 0;
>>> +
>>> +     wait_for_completion(&ts->firmware_loading_complete);
>>
>> This is not that nice as it may lead to angry splats from the PM core if
>> firmware loading takes too long and we start suspending before it
>> completes.
>
> What exactly do you mean?  The suspend watchdog or something else?

I was thinking about dpm watchdog that will panic the system if
suspend takes too long. Hmm, this is debug facility and the default
timeout is 60 seconds, so I guess we can ignore my concern.

>
>> Rafael, if we issue pm_stay_awake() before requesting firmware and
>> pm_relax() once it is done, will this prevent the current suspend
>> timeouts?
>
> pm_stay_awake() only works if the checking of wakeup sources is
> enabled which generally depends on what user space does.

I see.

Thanks.

-- 
Dmitry
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