linux-kernel - Re: [PATCH V2 2/2] Input: misc: introduce palmas-pwrbutton

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Message-ID: <20140821180300.GA5854@core.coreip.homeip.net>
Date:	Thu, 21 Aug 2014 11:03:00 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Nishanth Menon <nm@...com>
Cc:	"Murphy, Dan" <dmurphy@...com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH V2 2/2] Input: misc: introduce palmas-pwrbutton

On Thu, Aug 21, 2014 at 12:37:15PM -0500, Nishanth Menon wrote:
> On 12:32-20140821, Murphy, Dan wrote:
> > On 08/21/2014 12:19 PM, Menon, Nishanth wrote:
> > > On 08/21/2014 11:59 AM, Murphy, Dan wrote:
> > > [...]
> > > Ooops.. missed answering one addition statement:
> > > 
> > >>> +	of_property_read_u32(np, "ti,palmas-long-press-seconds", &val);
> > >>
> > >> Probably should check the return to make sure the value exists and that is is
> > >> within an expected range.
> > > It is an optional parameter and may not exist in dt. when it does
> > > exist, the logic tries to do a best match (this is the for loop in the
> > > logic just below).
> > > 
> > 
> > The issue is val might be returned as a negative which will then proceed to
> > set the config->long_press_time_val to the lowest time value which then overrides
> > your initial setting of config->long_press_time_val = ARRAY_SIZE(lpk_times) - 1;
> > 
> 
> Does the following as a replacement look OK? if yes, I can incorporate
> as part of v3 of this series.
> /**
>  * palmas_pwron_params_ofinit() - device tree parameter parser
>  * @dev:	palmas button device
>  * @config:	configuration params that this fills up
>  */
> static void palmas_pwron_params_ofinit(struct device *dev,
> 				       struct palmas_pwron_config *config)
> {
> 	struct device_node *np;
> 	u32 val;
> 	int i, ret;
> 	u8 lpk_times[] = { 6, 8, 10, 12 };
> 	int pwr_on_deb_ms[] = { 15, 100, 500, 1000 };
> 
> 	/* Handle cases where device node based configuration is not present */
> 	if (!of_have_populated_dt())
> 		return;
> 	np = of_node_get(dev->of_node);
> 	if (!np)
> 		return;
> 
> 	/* Default config parameters - least debounce, max long key press */
> 	config->pwron_debounce_val = 0;
> 	config->long_press_time_val = ARRAY_SIZE(lpk_times) - 1;
> 
> 	ret = of_property_read_u32(np, "ti,palmas-long-press-seconds", &val);
> 	if (ret)
> 		goto skip_lpk;

Just without gotos please. They are nice in error handling paths and in some
other rare circumstances, but not here.

> 	for (i = 0; i < ARRAY_SIZE(lpk_times); i++) {
> 		if (val <= lpk_times[i]) {
> 			config->long_press_time_val = i;
> 			break;
> 		}
> 	}
> 
> skip_lpk:
> 	ret = of_property_read_u32(np, "ti,palmas-pwron-debounce-milli-seconds",
> 				   &val);
> 	if (ret)
> 		goto skip_debounce;
> 	for (i = 0; i < ARRAY_SIZE(pwr_on_deb_ms); i++) {
> 		if (val <= pwr_on_deb_ms[i]) {
> 			config->pwron_debounce_val = i;
> 			break;
> 		}
> 	}
> 
> skip_debounce:
> 	dev_info(dev, "h/w controlled shutdown duration=%d seconds\n",
> 		 lpk_times[config->long_press_time_val]);
> 
> 	of_node_put(np);

BTW, I do not think you need to use of_node_get/put here, it's not going anywhere.

Thanks.

-- 
Dmitry
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