From: "Clément Péron" <peron.clem@gmail.com>
To: megous@megous.com, Chen-Yu Tsai <wens@csie.org>,
Alessandro Zummo <a.zummo@towertech.it>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Maxime Ripard <maxime.ripard@bootlin.com>,
linux-rtc@vger.kernel.org,
devicetree <devicetree@vger.kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-sunxi <linux-sunxi@googlegroups.com>
Subject: Re: [linux-sunxi] [PATCH 2/3] rtc: sun6i: Add support for H6 RTC
Date: Mon, 5 Aug 2019 14:16:29 +0200 [thread overview]
Message-ID: <CAJiuCcevAHm1_P8USuP1TxCDKH=eJ_CA0SC=sfZP=v03p5y_Yw@mail.gmail.com> (raw)
In-Reply-To: <20190805111037.76vmanzcurffpbdf@core.my.home>
Hi,
On Mon, 5 Aug 2019 at 13:10, Ondřej Jirman <megous@megous.com> wrote:
>
> On Mon, Aug 05, 2019 at 06:54:17PM +0800, Chen-Yu Tsai wrote:
> > On Mon, Aug 5, 2019 at 6:45 PM Ondřej Jirman <megous@megous.com> wrote:
> > >
[snip]
>
> Interesting. :) I have the BSP I was using saved here:
>
> https://megous.com/git/linux/tree/drivers/rtc/rtc-sunxi.c?h=h6-4.9-bsp#n649
>
> It's based of 4.9.119
>
> https://megous.com/git/linux/log/?h=h6-4.9-bsp
>
> I don't remember where I found it. But I imported it fairly recently, and
> the code you pointed to looks like an older version that I can found in some
> beta H6 BSP, that I imported way earlier and is based on 4.9.56:
The last recent that I know is from OrangePi H6 but it's based on 4.9.118.
https://github.com/orangepi-xunlong/OrangePiH6_Linux4_9
Regards,
Clément
>
> https://megous.com/git/linux/tree/drivers/rtc/rtc-sunxi.c?h=linux-h6
> https://megous.com/git/linux/log/?h=linux-h6
>
> Hmm, archeology. :)
>
> > > For older BSPs, the init sequence looked like this:
> > >
> > > 482 /*
> > > 483 * Step1: select RTC clock source
> > > 484 */
> > > 485 tmp_data = sunxi_rtc_read(SUNXI_LOSC_CTRL_REG);
> > > 486 tmp_data &= (~REG_CLK32K_AUTO_SWT_EN);
> > > 487 tmp_data |= (RTC_SOURCE_EXTERNAL | REG_LOSCCTRL_MAGIC);
> > > 488 tmp_data |= (EXT_LOSC_GSM);
> > > 489 sunxi_rtc_write(tmp_data, SUNXI_LOSC_CTRL_REG);
> > > 490
> > >
> > > EXT_LOSC_GSM has values 4 values from low to high, and I guess it configures
> > > gain for the oscillator's amplifier in the feedback loop of the circuit.
> > >
> > > So the new code, for some reason changed from single write to sequence
> > > of individual writes/config steps:
> > >
> > > 1) disable auto-switch and enable auto-switch bypass
> > > 2) select RTC clock source (to LOSC)
> > > (wait)
> >
> > Maybe it's possible to glitch if these two are combined?
>
> That's what I thought too. Or the programmer thought so, and was just
> programming defensively, and there's no real problem in the practice.
>
> But that specific delay() seems like someone trying to solve a real issue. Of
> course there's no knowing if it was on H6 or on some other SoC.
>
> regards,
> o.
>
> >
> > > 3) configure gain on the LOSC
> > >
> > > regards,
> > > o.
> > >
> > > > ChenYu
> > >
> > > --
> > > You received this message because you are subscribed to the Google Groups "linux-sunxi" group.
> > > To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscribe@googlegroups.com.
> > > To view this discussion on the web, visit https://groups.google.com/d/msgid/linux-sunxi/20190805104529.z3mex3m2tss7lzlr%40core.my.home.
>
> --
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next prev parent reply other threads:[~2019-08-05 12:16 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-12 12:07 [PATCH 0/3] Add basic support for RTC on Allwinner H6 SoC megous
2019-04-12 12:07 ` [PATCH 1/3] dt-bindings: Add compatible for H6 RTC megous
2019-08-05 10:16 ` [linux-sunxi] " Chen-Yu Tsai
2019-04-12 12:07 ` [PATCH 2/3] rtc: sun6i: Add support " megous
2019-08-05 10:16 ` [linux-sunxi] " Chen-Yu Tsai
2019-08-05 10:20 ` Ondřej Jirman
2019-08-05 10:45 ` Ondřej Jirman
2019-08-05 10:54 ` Chen-Yu Tsai
2019-08-05 11:10 ` Ondřej Jirman
2019-08-05 11:21 ` Chen-Yu Tsai
2019-08-05 12:16 ` Clément Péron [this message]
2019-04-12 12:07 ` [PATCH 3/3] arm64: dts: sun50i-h6: Add support for RTC and fix the clock tree megous
2019-04-15 8:18 ` [linux-sunxi] [PATCH 0/3] Add basic support for RTC on Allwinner H6 SoC Chen-Yu Tsai
2019-04-15 14:22 ` Ondřej Jirman
2019-04-15 14:33 ` Maxime Ripard
2019-04-15 14:39 ` Chen-Yu Tsai
2019-04-15 14:35 ` Chen-Yu Tsai
2019-04-15 15:17 ` Ondřej Jirman
2019-08-06 18:30 ` Ondřej Jirman
2019-08-06 22:27 ` Ondřej Jirman
2019-08-07 10:55 ` Alexandre Belloni
2019-08-08 5:48 ` Chen-Yu Tsai
2019-08-08 12:12 ` Ondřej Jirman
2019-08-08 23:39 ` Alexandre Belloni
2019-08-09 9:16 ` Ondřej Jirman
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