Re: [PATCH RFC 2/6] arm64: dts: qcom: ipq5424: Add the IMEM node

[Kathiravan Thirumoorthy]

On 4/11/2025 2:33 PM, Konrad Dybcio wrote:
> On 4/11/25 7:01 AM, Kathiravan Thirumoorthy wrote:
> > On 4/10/2025 12:11 AM, Konrad Dybcio wrote:
> > > On 4/8/25 10:49 AM, Kathiravan Thirumoorthy wrote:
> > > > Add the IMEM node to the device tree to extract debugging information
> > > > like system restart reason, which is populated via IMEM. Define the
> > > > IMEM region to enable this functionality. Corresponding DTS and driver
> > > > changes will be added incrementally.
> > > >
> > > > Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@xxxxxxxxxxxxxxxx>
> > > > ---
> > > >    arch/arm64/boot/dts/qcom/ipq5424.dtsi | 9 +++++++++
> > > >    1 file changed, 9 insertions(+)
> > > >
> > > > diff --git a/arch/arm64/boot/dts/qcom/ipq5424.dtsi b/arch/arm64/boot/dts/qcom/ipq5424.dtsi
> > > > index 5d6ed2172b1bb0a57c593f121f387ec917f42419..a772736f314f46d11c473160c522af4edeb900b7 100644
> > > > --- a/arch/arm64/boot/dts/qcom/ipq5424.dtsi
> > > > +++ b/arch/arm64/boot/dts/qcom/ipq5424.dtsi
> > > > @@ -486,6 +486,15 @@ ssphy_0: phy@7d000 {
> > > >                status = "disabled";
> > > >            };
> > > >    +        sram@8600000 {
> > > > +            compatible = "qcom,ipq5424-imem", "syscon", "simple-mfd";
> > > > +            reg = <0 0x08600000 0 0x1000>;
> > > > +            ranges = <0 0 0x08600000 0x1000>;
> > > It looks like this should be a little longer
> >
> > Yes. It is 112KB. But only first 4KB is accessible by all masters in the system, remaining regions are access protected by TZ. I shall mention this in the commit message in the next version.
> I think we should describe the full length of it - it's only if we
> add a subnode that we actually access it


Sure got it.  I will describe the full length in next revision. In that 
case, it would be the driver's responsibility not to go beyond the 
initial 4K.


> Konrad