Re: [PATCH 1/3] arm64: dts: qcom: sm8450: Add qfprom node

[Mukesh Ojha]

On 5/28/2024 9:07 PM, Bjorn Andersson wrote:
> On Sun, Mar 17, 2024 at 08:21:58PM GMT, Bjorn Andersson wrote:
> > On Thu, Mar 14, 2024 at 10:13:59PM +0530, Mukesh Ojha wrote:
> > > Sorry for the late reply, was on vacation.
> > >
> > > On 3/6/2024 9:24 PM, Konrad Dybcio wrote:
> > > > On 3/6/24 13:26, Mukesh Ojha wrote:
> > > > > Add the qfprom node for sm8450 SoC.
> > > > >
> > > > > Signed-off-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
> > > > > ---
> > > > >    arch/arm64/boot/dts/qcom/sm8450.dtsi | 7 +++++++
> > > > >    1 file changed, 7 insertions(+)
> > > > >
> > > > > diff --git a/arch/arm64/boot/dts/qcom/sm8450.dtsi
> > > > > b/arch/arm64/boot/dts/qcom/sm8450.dtsi
> > > > > index b86be34a912b..02089a388d03 100644
> > > > > --- a/arch/arm64/boot/dts/qcom/sm8450.dtsi
> > > > > +++ b/arch/arm64/boot/dts/qcom/sm8450.dtsi
> > > > > @@ -4575,6 +4575,13 @@
> > > > >                };
> > > > >            };
> > > > > +        qfprom: efuse@221c8000 {
> > > > > +            compatible = "qcom,sm8450-qfprom", "qcom,qfprom";
> > > > > +            reg = <0 0x221c8000 0 0x1000>;
> > > >
> > > > Is is really only 0x1000-long? Also, is the base you put
> > > > here the ECC-corrected part (if that still exists)?
> > >
> > > No, its not.
> > >
> > > Entire fuse space is this.
> > > 0x221C0000-0x221Cbfff
> > >
> > > ECC corrected range is this 0x221C2000-0x221C3fff and High level OS
> >
> > That's 0x2000. Does this then also imply that the ECC-corrected values
> > are no longer mapped 1:1 with non-corrected, or why do they differ in
> > size?
> >
> > > does have a access to ECC range however, they are not recommended for
> > > SW usage.
> > >
> > > Above mentioned SW range(4) in the patch is  one and only accessible range
> > > available out of 0-7 SW ranges(0x221C4000-0x221Cbfff with each
> > > size 0x1000) and does not have ECC fuses.
> >
> > So you're saying that in contrast to other platforms, the 4th software
> > range, dedicated for HLOS, does not have a matching ECC-corrected
> > shadow? If that's the case, then "not recommended for SW usage" sounds
> > wrong.
> >
> > > All the downstream use cases are getting fulfilled with this.
> >
> > You only need ECC if you're unlucky...
>
> The patch is either incorrect or the commit message is lacking answers
> to the questions from Konrad and myself.
>
> Would have appreciated a reply here, but either way I'm marking this as
> "changes requested" and dropping it from the queue.

Apology for coming late on this., it just skipped from my tracking.. 
Frankly, I don't have convincing answer apart from what reason are 
exposed to kernel to read for SoCs like sm8[456]0 , will try to get
the answer soon.

-Mukesh