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From: Maxime Ripard <maxime@cerno.tech>
To: Samuel Holland <samuel@sholland.org>
Cc: Icenowy Zheng <icenowy@sipeed.com>,
	Rob Herring <robh+dt@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Andre Przywara <andre.przywara@arm.com>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 15/17] arm64: allwinner: dts: add DTSI file for R329 SoC
Date: Wed, 25 Aug 2021 17:00:46 +0200	[thread overview]
Message-ID: <20210825150046.dpua45aeqrndxzbu@gilmour> (raw)
In-Reply-To: <8e4a49b8-8f17-d659-0952-0c96b0098139@sholland.org>

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On Thu, Aug 19, 2021 at 10:06:43PM -0500, Samuel Holland wrote:
> On 8/18/21 9:32 PM, Samuel Holland wrote:
> > On 8/18/21 4:15 AM, Icenowy Zheng wrote:
> >> 于 2021年8月18日 GMT+08:00 下午5:01:39, Maxime Ripard <maxime@cerno.tech> 写到:
> >>> On Mon, Aug 02, 2021 at 02:22:10PM +0800, Icenowy Zheng wrote:
> >>>> +		ccu: clock@2001000 {
> >>>> +			compatible = "allwinner,sun50i-r329-ccu";
> >>>> +			reg = <0x02001000 0x1000>;
> >>>> +			clocks = <&osc24M>, <&rtc 0>, <&rtc 2>;
> >>>> +			clock-names = "hosc", "losc", "iosc";
> >>>
> >>> Do we have a clock tree for the RTC? Is it the same than the H616?
> >>
> >> Nope, it's the same with H6 because of external LOSC crystal is
> >> possible. (Although production M2A SoMs has it NC for cost control.)
> > 
> > It is not the same as the H6, either. The clock tree _is_ identical to the D1,
> > which has three diagrams on pages 363-364 of its user manual here:
> > 
> > https://dl.linux-sunxi.org/D1/D1_User_Manual_V0.1_Draft_Version.pdf
> > 
> > Compared to the H6, the R329/D1:
> >  - Loses the LOSC calibration circuit
> >  - Gains a third mux input for LOSC (not external 32k) to fanout
> >  - Gains a mux to choose between LOSC and HOSC/750 for the RTC clock
> >  - Gains an SPI bus clock input divided from the PRCM AHB
> > 
> > Compared to the H616, the R329/D1:
> >  - Has an external 32k crystal input
> >    - Gains the IOSC vs. external 32k crystal mux for LOSC
> >    - Switches fanout mux input #1 from pll_periph0/N to external 32k
> >  - Gains a mux to choose between LOSC and HOSC/750 for the RTC clock
> >  - Gains an SPI bus clock input divided from the PRCM AHB
> > 
> > So the R329/D1 RTC has three^Wfour inputs:
> >  - SPI clock from PRCM
> >  - 24 MHz DCXO crystal
> >  - 32 kHz external crystal (optional)
> 
> Whoops, I missed one here:
>  - Bus clock from PRCM
> 
> The SPI clock is new for R329, but the bus clock has been around since H6.
> 
> > and four outputs:
> >  - 16 MHz "IOSC" RC oscillator
> >  - 32 kHz "LOSC"
> >  - ~1 kHz for RTC timekeeping
> 
> Even though this is internal to the RTC, it is still useful to model, as it can
> be used to correct for known RTC drift. (For example, HOSC/750 is 32000 Hz
> instead of 32768 Hz, so 2.34375% slow. But that is better than IOSC, which has
> unknown error.)

If it's not useful to any other device, there's no real reason to model
it in the clock framework. We should still force the source of the RTC
to the most accurate option we have, but we can do that without the CCF.

Maxime

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  reply	other threads:[~2021-08-25 15:00 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-02  6:21 [PATCH 00/17] Basical Allwinner R329 support Icenowy Zheng
2021-08-02  6:21 ` [PATCH 01/17] rtc: sun6i: Fix time overflow handling Icenowy Zheng
2021-08-02  6:21 ` [PATCH 02/17] rtc: sun6i: Add support for linear day storage Icenowy Zheng
2021-08-02  6:21 ` [PATCH 03/17] rtc: sun6i: Add support for broken-down alarm registers Icenowy Zheng
2021-08-02  6:21 ` [PATCH 04/17] dt-bindings: rtc: sun6i: add compatible string for R329 RTC Icenowy Zheng
2021-08-06 21:39   ` Rob Herring
2021-08-02  6:22 ` [PATCH 05/17] rtc: sun6i: add support " Icenowy Zheng
2021-08-02  6:22 ` [PATCH 06/17] dt-bindings: pinctrl: document Allwinner R329 PIO and R-PIO Icenowy Zheng
2021-08-06 21:40   ` Rob Herring
2021-08-18  8:48   ` Maxime Ripard
2021-08-19  2:40   ` Samuel Holland
2021-08-02  6:22 ` [PATCH 07/17] pinctrl: sunxi: add support for R329 CPUX pin controller Icenowy Zheng
2021-08-11  9:23   ` Linus Walleij
2021-08-18  8:48   ` Maxime Ripard
2021-08-19  3:09   ` Samuel Holland
2021-08-02  6:22 ` [PATCH 08/17] pinctrl: sunxi: add support for R329 R-PIO " Icenowy Zheng
2021-08-18  8:52   ` Maxime Ripard
2021-08-19  3:22   ` Samuel Holland
2021-08-02  6:22 ` [PATCH 09/17] dt-bindings: clock: sunxi-ng: add compatibles for R329 CCUs Icenowy Zheng
2021-08-06 21:41   ` Rob Herring
2021-08-02  6:22 ` [PATCH 10/17] clk: sunxi=ng: add support for R329 R-CCU Icenowy Zheng
2021-08-06 21:42   ` Rob Herring
2021-08-18  8:50   ` Maxime Ripard
2021-08-20  0:55   ` Samuel Holland
2021-08-20  4:34     ` Jernej Škrabec
2021-08-25 14:50       ` Maxime Ripard
2021-08-25 15:03         ` Jernej Škrabec
2021-08-25 15:37           ` Maxime Ripard
2021-08-26  0:20       ` Samuel Holland
2021-08-02  6:22 ` [PATCH 11/17] clk: sunxi-ng: add support for Allwinner R329 CCU Icenowy Zheng
2021-08-06 21:42   ` Rob Herring
2021-08-20  2:41   ` Samuel Holland
2021-08-25 14:54     ` Maxime Ripard
2021-08-02  6:22 ` [PATCH 12/17] dt-bindings: mmc: sunxi-mmc: add R329 MMC compatible string Icenowy Zheng
2021-08-06 21:42   ` Rob Herring
2021-08-18  8:47   ` Maxime Ripard
2021-08-02  6:22 ` [PATCH 13/17] mmc: sunxi: add support for R329 MMC controllers Icenowy Zheng
2021-08-18  8:47   ` Maxime Ripard
2021-08-20  2:43   ` Samuel Holland
2021-08-02  6:22 ` [PATCH 14/17] dt-bindings: arm: sunxi: add compatible strings for Sipeed MaixSense Icenowy Zheng
2021-08-06 21:43   ` Rob Herring
2021-08-18  9:03   ` Maxime Ripard
2021-08-02  6:22 ` [PATCH 15/17] arm64: allwinner: dts: add DTSI file for R329 SoC Icenowy Zheng
2021-08-18  9:01   ` Maxime Ripard
     [not found]     ` <74F51516-2470-4A49-972B-E19D8EDD9A3D@sipeed.com>
2021-08-19  2:32       ` Samuel Holland
2021-08-20  3:06         ` Samuel Holland
2021-08-25 15:00           ` Maxime Ripard [this message]
2021-08-20  2:59   ` Samuel Holland
2021-08-02  6:22 ` [PATCH 16/17] arm64: allwinner: dts: r329: add DTSI file for Sipeed Maix IIA Icenowy Zheng
2021-08-02  6:22 ` [PATCH 17/17] arm64: allwinner: dts: r329: add support for Sipeed MaixSense Icenowy Zheng
2021-08-10 11:04 ` [PATCH 00/17] Basical Allwinner R329 support Ulf Hansson

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