From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Esteban Blanc <eblanc@baylibre.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 15:34:29 +0200 [thread overview]
Message-ID: <20230328133429ff45c492@mail.local> (raw)
In-Reply-To: <CRI1AQ7OIF6F.2G26C7VQKL5P0@burritosblues>
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.
--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2023-03-28 13:35 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 [this message]
2023-03-28 13:59 ` Esteban Blanc
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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