Message-ID: <bc4a7c9e47b1b102f27831509564fc44@manjaro.org>
Date: Tue, 09 Jul 2024 10:40:58 +0200
From: Dragan Simic <dsimic@...jaro.org>
To: Diederik de Haas <didi.debian@...ow.org>
Cc: Heiko Stuebner <heiko@...ech.de>, Alex Bee <knaerzche@...il.com>,
 linux-rockchip@...ts.infradead.org, devicetree@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: rockchip: Add avdd supplies to hdmi on rock64

Hello Diederik,

On 2024-07-08 11:55, Diederik de Haas wrote:
> On Sunday, 7 July 2024 23:23:30 CEST Dragan Simic wrote:
>> On 2024-07-04 21:18, Diederik de Haas wrote:
>> > Pine64's Rock64 was missing the avdd supply properties on the hdmi
>> > node,
>> >
>> > causing the following warnings:
>> >   dwhdmi-rockchip ff3c0000.hdmi: supply avdd-0v9 not found, using
>> > dummy regulator
>> >
>> >   dwhdmi-rockchip ff3c0000.hdmi: supply avdd-1v8 not found, using
>> > dummy regulator
>> >
>> > In the Rock64 Schematic document version 2.0 those supplies are marked
>> > as DVIDEO_AVDD_1V0 and DVIDEO_AVDD_1V8 respectively, but in version 3.0
>> > those are named HDMI_AVDD_1V0 and HDMI_AVDD_1V8, which is a bit
>> > clearer.
>> > In both versions those are connected to LDO3 and LDO1 respectively.
>> >
>> > While the DeviceTree property is named 'avdd-0v9-supply' the
>> >
>> > 'rockchip,dw-hdmi.yaml' binding document notes the following:
>> >   A 0.9V supply that powers up the SoC internal circuitry. The actual
>> >   pin name varies between the different SoCs and is usually
>> >   HDMI_TX_AVDD_0V9 or sometimes HDMI_AVDD_1V0.
>> >
>> > So the 'vdd_10' reference is not an error.
>> >
>> > Signed-off-by: Diederik de Haas <didi.debian@...ow.org>
>> 
>> Already verified the above-quoted statement from the .yaml binding
>> in the RK3328 and RK3399 datasheets.  Thus, hoping that you agree
>> with the first line:
>> 
>> Helped-by: Dragan Simic <dsimic@...jaro.org>
> 
> While you helped me in several areas (understanding 'things') and I 
> think
> proper attribution is very important, in this case it would be 
> incorrect IMO.
> I was helped by Heiko's (big) hint in their counter-proposal (which 
> does
> deserve a Helped-by tag), from that point on, it was all my own work.
> 
> After Heiko's counter-proposal I had found the regulator I needed to
> reference. I then resolved the DVIDEO vs HDMI remark by looking at v2 
> and v3
> of the Schematic document. Which left 1 thing to resolve ...
> 
> On Thursday, 4 July 2024 12:34:18 CEST Diederik de Haas wrote:
>> I do wonder about 0.9V vs 1.0V, but I'll bug someone else about that 
>> ;-)
> 
> I did mean you with that, but in the end I did resolve it myself.
> I found the 'note' in the binding document and when I then found "min: 
> 0.9;
> typical: 1.0; max: 1.1" in para 3.2 (page 36) of the RK3328 Datasheet, 
> I felt
> I had resolved that issue sufficiently as well and was confident enough 
> to sent
> the patch out (without sending you a RFC patch first).
> 
>> Reviewed-by: Dragan Simic <dsimic@...jaro.org>
> 
> Thanks :-)
> 
>> I'd also suggest that a brief comment is added to rk3328-rock64.dts,
>> right above the "avdd-0v9-supply = <&vdd_10>;" line.  Perhaps 
>> something
>> 
>> like this:
>> > +	/*
>> > +	 * RK3328 requires 1.0 V on HDMI_AVDD_1V0, which is HDMI_AVDD_0V9
>> > +	 * and requires 0.9 V on other Rockchip SoCs
>> > +	 */
> 
> The binding doc mention this: "The actual pin name varies between the 
> different
> SoCs and is *usually* HDMI_TX_AVDD_0V9" (emphasis mine)
> 
> So that comment would make stronger claims then is present in the 
> binding
> document and also uses a different pin name. I also don't think it's 
> useful to
> mention what other SoCs (or boards) use in the rk3328-rock64.dts.
> 
> While I fully agree that the apparent discrepancy should be documented, 
> I
> choose to do that in the commit message and I don't see a value to 
> repeat that
> in the dts file itself.
> When I see something which looks 'odd', I'd then use `git blame` to 
> find the
> commit which set that and then I'd see the commit message which 
> explains it.

Just for the record, I'm fine with your decisions.

>> > ---
>> >
>> >  arch/arm64/boot/dts/rockchip/rk3328-rock64.dts | 2 ++
>> >  1 file changed, 2 insertions(+)
>> >
>> > diff --git a/arch/arm64/boot/dts/rockchip/rk3328-rock64.dts
>> > b/arch/arm64/boot/dts/rockchip/rk3328-rock64.dts
>> > index 229fe9da9c2d..90fef766f3ae 100644
>> > --- a/arch/arm64/boot/dts/rockchip/rk3328-rock64.dts
>> > +++ b/arch/arm64/boot/dts/rockchip/rk3328-rock64.dts
>> > @@ -154,6 +154,8 @@ &gmac2io {
>> >
>> >  };
>> >
>> >  &hdmi {
>> >
>> > +	avdd-0v9-supply = <&vdd_10>;
>> > +	avdd-1v8-supply = <&vcc_18>;
>> >
>> >  	status = "okay";
>> >
>> >  };
> 
> 
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