Re: [RFC PATCH v2 7/7] arm64: dts: qcom: Add the Inline Crypto Engine nodes

[Eric Biggers <ebiggers@kernel.org>]

On Thu, Mar 09, 2023 at 11:31:46AM +0100, Krzysztof Kozlowski wrote:
> On 08/03/2023 16:58, Abel Vesa wrote:
> > Drop all properties related to ICE from every UFS and SDCC node,
> > for all platforms, and add dedicated ICE nodes for each platform.
> > On most platforms, there is only one ICE instance, used by either
> > UFS or SDCC, but there are some platforms that have two separate
> > instances and, therefore, two separate nodes are added.
> > 
> > Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
> > ---
> > 
> > Changes since v1:
> >  * Made changes for all platforms that use ICE, as a single patch since
> >    most changes look really similar.
> > 
> >  arch/arm64/boot/dts/qcom/sdm630.dtsi | 18 +++++++++-----
> >  arch/arm64/boot/dts/qcom/sdm670.dtsi | 15 +++++++----
> >  arch/arm64/boot/dts/qcom/sdm845.dtsi | 21 +++++++++-------
> >  arch/arm64/boot/dts/qcom/sm6115.dtsi | 37 +++++++++++++++++-----------
> >  arch/arm64/boot/dts/qcom/sm6350.dtsi | 31 ++++++++++++++---------
> >  arch/arm64/boot/dts/qcom/sm8150.dtsi | 21 +++++++++-------
> >  arch/arm64/boot/dts/qcom/sm8450.dtsi | 22 ++++++++++-------
> >  7 files changed, 102 insertions(+), 63 deletions(-)
> > 
> > diff --git a/arch/arm64/boot/dts/qcom/sdm630.dtsi b/arch/arm64/boot/dts/qcom/sdm630.dtsi
> > index 5827cda270a0..2aed49104d9d 100644
> > --- a/arch/arm64/boot/dts/qcom/sdm630.dtsi
> > +++ b/arch/arm64/boot/dts/qcom/sdm630.dtsi
> > @@ -1330,9 +1330,8 @@ opp-200000000 {
> >  		sdhc_1: mmc@c0c4000 {
> >  			compatible = "qcom,sdm630-sdhci", "qcom,sdhci-msm-v5";
> >  			reg = <0x0c0c4000 0x1000>,
> > -			      <0x0c0c5000 0x1000>,
> > -			      <0x0c0c8000 0x8000>;
> > -			reg-names = "hc", "cqhci", "ice";
> > +			      <0x0c0c5000 0x1000>;
> > +			reg-names = "hc", "cqhci";
> 
> I believe this will break the ICE on these platforms without valid
> reason. The commit msg does not explain why you do it or why this is
> necessary.
> 
> We already we received comment that we keep breaking Qualcomm platforms
> all the time and need to keep them in some shape.
> 
> Also, patchset is non-applicable in current set (breaks users) and
> neither commit nor cover letter mentions it.
> 

FWIW, I tested this patchset on SDA845, and ICE continues to work fine.

(Though if I understand the patchset correctly, the ICE clock is no longer
turned off when the UFS host controller is suspended.  That isn't ideal as it
wastes power.  I would like that to be fixed.)

Anyway, when you say "break the ICE", do you really mean "make an incompatible
change to the device-tree bindings"?

I'd think there would be no problem with that as long as everything is updated
at once, which this patchset does.

I've heard before that some people consider the device-tree bindings to be a
stable UAPI.  That doesn't make sense to me.  Actually, my original ICE patches
ran into this issue too, and the resolution was simply that the Qualcomm
platforms maintainer (Bjorn) decided to take the patches anyway.  I never heard
any complaints afterwards.  Maybe the same is fine here too?

- Eric