RE: [PATCH] rtc: tps65910: Add RTC driver for TPS65910 PMIC RTC

From: Venu Byravarasu
Date: Mon Jul 30 2012 - 06:09:25 EST


Thanks Stephen for your comments.
Plz see my comments inline.


> -----Original Message-----
> From: Stephen Boyd [mailto:sboyd@xxxxxxxxxxxxxx]
> Sent: Monday, July 30, 2012 2:47 PM
> To: Venu Byravarasu
> Cc: a.zummo@xxxxxxxxxxxx; sameo@xxxxxxxxxxxxxxx;
> broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx; Laxman Dewangan;
> kyle.manna@xxxxxxxxx; rtc-linux@xxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] rtc: tps65910: Add RTC driver for TPS65910 PMIC RTC
>
> On 7/25/2012 11:35 PM, Venu Byravarasu wrote:
> > +
> > +static struct rtc_class_ops tps65910_rtc_ops = {
>
> const?

Will add it in my next patch.

>
> > + .read_time = tps65910_rtc_read_time,
> > + .set_time = tps65910_rtc_set_time,
> > + .read_alarm = tps65910_rtc_read_alarm,
> > + .set_alarm = tps65910_rtc_set_alarm,
> > + .alarm_irq_enable = tps65910_rtc_alarm_irq_enable,
> > +};
> > +
> > +static int __devinit tps65910_rtc_probe(struct platform_device *pdev)
> > +{
> > + struct tps65910 *tps65910 = NULL;
> > + struct tps65910_rtc *tps_rtc = NULL;
> > + struct tps65910_board *pmic_plat_data;
> > + int ret = -EINVAL;
> > + int irq = 0;
> > + u32 rtc_reg;
>
> It seems like all the above assignments are useless as they're
> overwritten later in this function. Can you remove the assignments?
>

Some of the non-intelligent compilers/tools complain as variables
may get used uninitialized. Hence to avoid such complaints, initialized
them to some default values.
What harm do you see if I have local variables initialized during their declaration?

> > +
> > + tps65910 = dev_get_drvdata(pdev->dev.parent);
> > +
> > + tps_rtc = devm_kzalloc(&pdev->dev, sizeof(struct tps65910_rtc),
> > + GFP_KERNEL);
> > + if (!tps_rtc)
> > + return -ENOMEM;
> > +
> > + /* Clear pending interrupts */
> > + ret = regmap_read(tps65910->regmap, TPS65910_RTC_STATUS,
> &rtc_reg);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_write(tps65910->regmap, TPS65910_RTC_STATUS,
> rtc_reg);
> > + if (ret < 0)
> > + return ret;
> > +
> > + dev_dbg(&pdev->dev, "Enabling tps65910-RTC.\n");
>
> Hmph, looks more like stopping the RTC.
>

No, the register is a misnomer here.
As per data sheet of TPS65910, setting this bit will start RTC,
instead of stopping as its name suggests.


> > + rtc_reg = TPS65910_RTC_CTRL_STOP_RTC;
> > + ret = regmap_write(tps65910->regmap, TPS65910_RTC_CTRL,
> rtc_reg);
> > + if (ret < 0)
> > + return ret;
> > +
> > + pmic_plat_data = dev_get_platdata(tps65910->dev);
> > + irq = pmic_plat_data->irq_base;
> > + if (irq <= 0) {
> > + dev_warn(&pdev->dev, "Wake up is not possible as irq =
> %d\n",
> > + irq);
> > + return ret;
> > + }
> > +
> > + irq += TPS65910_IRQ_RTC_ALARM;
> > + ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
> > + tps65910_rtc_interrupt, IRQF_TRIGGER_LOW,
> > + dev_name(&tps_rtc->rtc->dev), &pdev->dev);
>
> How does this work? It doesn't look like tps_rtc->rtc is assigned until
> down there at the rtc_device_register() call.
>

Somehow this got skipped. Thanks for pointing out.
Will fix and push as part of next patch.


> > + if (ret < 0) {
> > + dev_err(&pdev->dev, "IRQ is not free.\n");
> > + return ret;
> > + }
> > + device_init_wakeup(&pdev->dev, 1);
> > +
> > + tps_rtc->rtc = rtc_device_register(pdev->name, &pdev->dev,
> > + &tps65910_rtc_ops, THIS_MODULE);
> > + if (IS_ERR(tps_rtc->rtc)) {
> > + ret = PTR_ERR(tps_rtc->rtc);
> > + dev_err(&pdev->dev, "RTC device register: err %d\n", ret);
> > + return ret;
> > + }
> > +
>
> --
> Sent by an employee of the Qualcomm Innovation Center, Inc.
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
> Forum.

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