Re: [PATCH 01/14] dt-bindings: watchdog: sunxi: fix F1C100s compatible

From: Andre Przywara <andre.przywara@arm.com>
To: Samuel Holland <samuel@sholland.org>
Cc: Maxime Ripard <mripard@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mesih Kilinc <mesihkilinc@gmail.com>,
	Icenowy Zheng <icenowy@aosc.io>,
	Jesse Taube <mr.bossman075@gmail.com>,
	Giulio Benetti <giulio.benetti@benettiengineering.com>,
	George Hilliard <thirtythreeforty@gmail.com>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-sunxi@lists.linux.dev,
	Wim Van Sebroeck <wim@linux-watchdog.org>,
	Guenter Roeck <linux@roeck-us.net>,
	linux-watchdog@vger.kernel.org
Subject: Re: [PATCH 01/14] dt-bindings: watchdog: sunxi: fix F1C100s compatible
Date: Mon, 14 Mar 2022 17:39:16 +0000	[thread overview]
Message-ID: <20220314173839.2a7b593a@slackpad.lan> (raw)
In-Reply-To: <661806b7-d63f-a7cf-9192-f67c4cd79f29@sholland.org>

On Wed, 9 Mar 2022 18:46:46 -0600
Samuel Holland <samuel@sholland.org> wrote:

> Hi Andre,
> 
> On 3/7/22 8:34 AM, Andre Przywara wrote:
> > The F1C100 series actually features a newer generation watchdog IP, so
> > the compatible string was wrong.  
> 
> The F1C100s watchdog seems to be unique in that it uses LOSC/osc32k as its only
> clock source instead of HOSC/osc24M. The current binding requires that the first
> clock is "hosc", so it seems that the binding needs to be relaxed to allow for
> this case.
> 
> As long as there's only one clock source available, we don't really care where
> it comes from. They are both divided to be approximately 32 kHz. So I don't
> think this difference prevents using A31 as a fallback compatible.

Right, these were roughly my findings as well, but I should have
written them down, at least in the commit message.

So shall the binding be explicit:
1) Most SoCs required exactly one clock, the 24 MHz HOSC.
2) The F1C100s requires exactly one clock, the 32KHz LOSC.
3) R329/D1 require two clocks with clock-names?

Or do you want to collapse 1) and 2) into one relaxed case? Still not
entirely sure what "LOSC / 32 KHz" means for the F1C100 (32768 or 32000
Hz), or where it really comes from, but it does not seem to matter.

FreeBSD, Xen and U-Boot don't care about clocks at all, and Linux
always uses the first clock and just enables it, so we should be good
either way.

> 
> > Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> > ---
> >  .../devicetree/bindings/watchdog/allwinner,sun4i-a10-wdt.yaml   | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/watchdog/allwinner,sun4i-a10-wdt.yaml b/Documentation/devicetree/bindings/watchdog/allwinner,sun4i-a10-wdt.yaml
> > index 43afa24513b9..d90655418d0e 100644
> > --- a/Documentation/devicetree/bindings/watchdog/allwinner,sun4i-a10-wdt.yaml
> > +++ b/Documentation/devicetree/bindings/watchdog/allwinner,sun4i-a10-wdt.yaml
> > @@ -29,7 +29,7 @@ properties:
> >            - const: allwinner,sun6i-a31-wdt
> >        - items:
> >            - const: allwinner,suniv-f1c100s-wdt
> > -          - const: allwinner,sun4i-a10-wdt
> > +          - const: allwinner,sun6i-a31-wdt  
> 
> This can be combined with the enum of other compatibles that fall back to
> allwinner,sun6i-a31-wdt (earlier in the file).

Oh, right, I missed that.

Cheers,
Andre

> 
> Regards,
> Samuel
> 
> >        - const: allwinner,sun20i-d1-wdt
> >        - items:
> >            - const: allwinner,sun20i-d1-wdt-reset
> >   
> 
> 

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