linux-kernel - Re: [PATCH 1/4] arm64: dts: qcom: sc8280xp: rename i2c5 to i2c21

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Message-ID: <Y5iXjTQnEtMCZy7W@hovoldconsulting.com>
Date:   Tue, 13 Dec 2022 16:17:33 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Brian Masney <bmasney@...hat.com>
Cc:     andersson@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        konrad.dybcio@...aro.org, robh+dt@...nel.org,
        johan+linaro@...nel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        ahalaney@...hat.com, echanude@...hat.com, quic_shazhuss@...cinc.com
Subject: Re: [PATCH 1/4] arm64: dts: qcom: sc8280xp: rename i2c5 to i2c21

On Tue, Dec 13, 2022 at 03:54:05PM +0100, Johan Hovold wrote:
> On Mon, Dec 12, 2022 at 01:23:11PM -0500, Brian Masney wrote:
> > According to the downstream 5.4 kernel sources for the sa8540p,
> > i2c@...000 is labeled i2c bus 21, not 5. The interrupts and clocks
> > also match. Let's go ahead and correct the name that's used in the
> > three files where this is listed.
> > 
> > Signed-off-by: Brian Masney <bmasney@...hat.com>
> > Fixes: 152d1faf1e2f3 ("arm64: dts: qcom: add SC8280XP platform")
> > Fixes: ccd3517faf183 ("arm64: dts: qcom: sc8280xp: Add reference device")
> > Fixes: 32c231385ed43 ("arm64: dts: qcom: sc8280xp: add Lenovo Thinkpad X13s devicetree")
> 
> > diff --git a/arch/arm64/boot/dts/qcom/sc8280xp.dtsi b/arch/arm64/boot/dts/qcom/sc8280xp.dtsi
> > index 109c9d2b684d..875cc91324ce 100644
> > --- a/arch/arm64/boot/dts/qcom/sc8280xp.dtsi
> > +++ b/arch/arm64/boot/dts/qcom/sc8280xp.dtsi
> > @@ -827,7 +827,7 @@ qup2_uart17: serial@...000 {
> >  				status = "disabled";
> >  			};
> >  
> > -			qup2_i2c5: i2c@...000 {
> > +			qup2_i2c21: i2c@...000 {
> 
> Note that the node is labelled qup2_i2c5 and not qup_i2c5.
> 
> That is, the QUP nodes are labelled using two indices, and specifically
> 
> 	qup2_i2c5
> 
> would be another name for
> 
> 	qup_i2c21
> 
> if we'd been using such a flat naming scheme (there are 8 engines per
> QUP).
> 
> So there's nothing wrong with how these nodes are currently named, but
> mixing the two scheme as you are suggesting would not be correct.

It appears sc8280xp is the only qcom platform using a qup prefix (even
if some older platform use a blsp equivalent), and we're not even using
it consistently as we, for example, have both

	qup2_uart17, and
	qup2_i2c5

(where the former should have been qup2_uart1).

So either we fix up the current labels or just drop the qup prefixes and
use a flat naming scheme (e.g. uart17 and i2c21).

Either way, there's no need for any Fixes tags as this isn't a bug.

Johan