From: "Esteban Blanc" <eblanc@baylibre.com>
To: "Alexandre Belloni" <alexandre.belloni@bootlin.com>
Cc: <linus.walleij@linaro.org>, <lgirdwood@gmail.com>,
<broonie@kernel.org>, <a.zummo@towertech.it>,
<linux-kernel@vger.kernel.org>, <linux-gpio@vger.kernel.org>,
<linux-rtc@vger.kernel.org>, <jpanis@baylibre.com>,
<jneanne@baylibre.com>, <sterzik@ti.com>, <u-kumar1@ti.com>
Subject: Re: [PATCH v2 1/3] rtc: tps6594: add driver for TPS6594 PMIC RTC
Date: Tue, 28 Mar 2023 15:59:58 +0200 [thread overview]
Message-ID: <CRI2JTK76CHY.PX9MOKSRGSE5@burritosblues> (raw)
In-Reply-To: <20230328133429ff45c492@mail.local>
On Tue Mar 28, 2023 at 3:34 PM CEST, Alexandre Belloni wrote:
> On 28/03/2023 15:01:05+0200, Esteban Blanc wrote:
> > On Tue Mar 28, 2023 at 11:29 AM CEST, Alexandre Belloni wrote:
> > > Hello,
> > >
> > > On 28/03/2023 11:14:46+0200, Esteban Blanc wrote:
> > > > + /* Start rtc */
> > > > + ret = regmap_set_bits(tps->regmap, TPS6594_REG_RTC_CTRL_1,
> > > > + TPS6594_BIT_STOP_RTC);
> > > > + if (ret < 0)
> > > > + return ret;
> > > > +
> > > > + mdelay(100);
> > > > +
> > > > + /*
> > > > + * RTC should be running now. Check if this is the case.
> > > > + * If not it might be a missing oscillator.
> > > > + */
> > > > + ret = regmap_test_bits(tps->regmap, TPS6594_REG_RTC_STATUS,
> > > > + TPS6594_BIT_RUN);
> > > > + if (ret < 0)
> > > > + return ret;
> > > > + if (ret == 0)
> > > > + return -ENODEV;
> > > > +
> > > > + /* Stop RTC until first call to `tps6594_rtc_set_time */
> > > > + ret = regmap_clear_bits(tps->regmap, TPS6594_REG_RTC_CTRL_1,
> > > > + TPS6594_BIT_STOP_RTC);
> > > > + if (ret < 0)
> > > > + return ret;
> > > > +
> > >
> > > This whole block must not be executed when the RTC is already running,
> > > else, you are stopping a perfectly running RTC.
> >
> > I'm not sure to get your point. You mean that during probe, the driver
> > might encounter an RTC device that is already running with a correct
> > timestamp? How would this be possible? A previous bootstage or the
> > driver was removed then re-inserted again?
> >
>
> The whole point of having an RTC is that the time tracking survives a
> reboot so yes, I would expect the RTC to have a valid timestamp at probe
> time.
Oh. Oh I see. I did not think of that. I will add a check for that.
Thanks again,
--
Esteban Blanc
BayLibre
next prev parent reply other threads:[~2023-03-28 14:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-28 9:14 [PATCH v2 0/3] TI TPS6594 PMIC support (RTC, pinctrl, regulators, device trees) Esteban Blanc
2023-03-28 9:14 ` [PATCH v2 1/3] rtc: tps6594: add driver for TPS6594 PMIC RTC Esteban Blanc
2023-03-28 9:29 ` Alexandre Belloni
2023-03-28 13:01 ` Esteban Blanc
2023-03-28 13:34 ` Alexandre Belloni
2023-03-28 13:59 ` Esteban Blanc [this message]
2023-03-28 9:14 ` [PATCH v2 2/3] pinctrl: tps6594: add for TPS6594 PMIC Esteban Blanc
2023-03-28 9:14 ` [PATCH v2 3/3] regulator: tps6594-regulator: Add driver for TI TPS6594 regulators Esteban Blanc
2023-03-28 20:09 ` kernel test robot
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