linux-kernel - Re: [PATCH v7 2/3] rtc: sophgo: add rtc support for Sophgo CV1800 SoC

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Date: Mon, 22 Jan 2024 17:23:30 +0800
From: Jingbao Qiu <qiujingbao.dlmu@...il.com>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org, 
	chao.wei@...hgo.com, unicorn_wang@...look.com, paul.walmsley@...ive.com, 
	palmer@...belt.com, aou@...s.berkeley.edu, linux-rtc@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, dlan@...too.org
Subject: Re: [PATCH v7 2/3] rtc: sophgo: add rtc support for Sophgo CV1800 SoC

On Mon, Jan 22, 2024 at 5:15 PM Alexandre Belloni
<alexandre.belloni@...tlin.com> wrote:
>
> On 22/01/2024 16:34:00+0800, Jingbao Qiu wrote:
> > On Mon, Jan 22, 2024 at 4:17 PM Alexandre Belloni
> > <alexandre.belloni@...tlin.com> wrote:
> > >
> > > On 22/01/2024 16:06:30+0800, Jingbao Qiu wrote:
> > > > Implement the RTC driver for CV1800, which able to provide time alarm
> > > > and calibrate functionality.
> > > >
> > > > Signed-off-by: Jingbao Qiu <qiujingbao.dlmu@...il.com>
> > > > ---
> > > >
> > > > Depends on https://lore.kernel.org/all/IA1PR20MB4953C774D41EDF1EADB6EC18BB6D2@IA1PR20MB4953.namprd20.prod.outlook.com/
> > >
> > > What is the dependency?
> > >
> >
> > Thank you, this driver requires support from the CLK driver.
> > I will add an explanation in the next version.
> >
> > >
> > > Also, please fix the checkpatch.pl --strict warnings
> >
> > I will use the -- strict option for testing.
> >
> > >
> > > > +/**
> > > > + * cv1800_rtc_32k_coarse_val_calib() - Using an external
> > > > + * clock to coarse calibrate the crystal oscillator
> > > > + * @info: the device of calibrated
> > > > + *
> > > > + * @return 0 on success, or -1 on fail
> > > > + *
> > > > + * This RTC has an independent 32KHz oscillator. However,
> > > > + * the accuracy of this oscillator is easily affected by
> > > > + * external environmental interference,resulting in lower
> > > > + * accuracy than the internal oscillator.Therefore, a 25M
> > > > + * crystal oscillator is used as a reference source to
> > > > + * calibrate the RTC and improve its accuracy.Calibration
> > > > + * is completed through two steps, namely rough calibration
> > > > + * and fine calibration.
> > > > + */
> > > > +static int cv1800_rtc_32k_coarse_val_calib(struct cv1800_rtc_priv *info)
> > >
> > > This is still not working as well as you think it is. You should
> > > Implement the offset callbacks instead.
> > >
> > I'm sorry, I don't quite understand offset callbacks.
> > Do you mean that this function needs to be executed periodically.
>
> I mean implement read_offset and set_offset here:
> https://elixir.bootlin.com/linux/v6.7/source/include/linux/rtc.h#L67
>

Thank you for your patient reply.
I will do that.

Best regards,
Jingbao Qiu