Re: [PATCH v3 1/2] dt-bindings: soc: qcom: Add qcom,kaanapali-imem compatible

[Kathiravan Thirumoorthy]

On 11/11/2025 5:38 PM, Aiqun(Maria) Yu wrote:
> On 11/11/2025 4:29 PM, Kathiravan Thirumoorthy wrote:
> > On 11/7/2025 1:54 AM, Bjorn Andersson wrote:
> > > On Tue, Nov 04, 2025 at 03:58:27PM +0100, Konrad Dybcio wrote:
> > > > On 11/4/25 3:52 PM, Krzysztof Kozlowski wrote:
> > > > > On 04/11/2025 15:38, Konrad Dybcio wrote:
> > > > > > On 11/4/25 3:37 PM, Krzysztof Kozlowski wrote:
> > > > > > > On 04/11/2025 15:35, Konrad Dybcio wrote:
> > > > > > > > On 11/4/25 3:26 PM, Krzysztof Kozlowski wrote:
> > > > > > > > > This I got, but nothing here explains why you need generic
> > > > > > > > > compatible.
> > > > > > > > > To re-iterate: there was no generic compatible before, now there
> > > > > > > > > is.
> > > > > > > > > Writing bindings and numerous reviews from DT maintainers ask
> > > > > > > > > not to use
> > > > > > > > > generic compatibles.
> > > > > > > > OK so let's not worry about a generic compatible. IMEM exists since
> > > > > > > > MSM8974 and it only had major hw updates with SM8550. They don't
> > > > > > > > impact the software interface though, so qcom,msm8974-imem is OK.
> > > > > > > >
> > > > > > > > There's a separate control/status register address space for each
> > > > > > > > instance of this IP (usually far apart from the actual SRAM pool),
> > > > > > > > which Linux doesn't have to care about.
> > > > > > > Just use qcom,kaanapali-imem - that's the first device here
> > > > > > > without syscons.
> > > > > > So we don't want to move the existing ones over?
> > > > > This was never discussed and this patch did not do it. You cannot move
> > > > > them, that's ABI.
> > > > I see, I implicitly assumed this would be a sweeping change.
> > > >
> > > > So should the Kaanapali submitters simply send a version of this
> > > > patch with:
> > > >
> > > > - oneOf:
> > > >     - const: qcom,kaanapali-imem
> > > >     - items:
> > > >       # existing big list
> > > >
> > > > ?
> > > We have 33 cases of "this is just a generic Qualcomm IMEM block", could
> > > we just make it "qcom,imem" until there's actually a sign that it's not
> > > a platform-independent block?
> If it’s not platform-specific, why not use a common compatible here? I
> mean let's have a common "qcom,imem" start from kaanapali.
>
> What benefits would a platform-specific approach bring in this case? For
> newer platforms, we could simply adopt the common compatible and avoid
> adding a dedicated platform compatible name.
>
> Also, the old bootloader reboot-mode solution that uses the IMEM area as
> a magic syscon is deprecated for newer targets.
>
> > Any conclusion / further feedback on this would be helpful to move
> > things forward. Thanks in advance.
>
> Which platform are you waiting for as a reference? Or are you only
> focused on the current Kaanapali?
> By the way, great to see we share the same goal here.


I'm working on the IPQ SoCs. All of these discussions started from the 
IPQ series[1], followed by Konrad's IPA stuff[2] and now we are in 
Kaanapali.

[1] 
https://lore.kernel.org/linux-arm-msm/20250610-wdt_reset_reason-v5-0-2d2835160ab5@xxxxxxxxxxxxxxxx/ 


[2] 
https://lore.kernel.org/linux-arm-msm/20250527-topic-ipa_imem-v2-0-6d1aad91b841@xxxxxxxxxxxxxxxx/

Reaching a conclusion on this topic together will help us move forward 
with the above mentioned series.


> > > Regards,
> > > Bjorn
> > >
> > > > I'm not a huge fan of using kaanapali as the fallback-going-forward
> > > > since it's literally the newest platform on the shelves (or perhaps
> > > > not even on the shelves yet..) so it's going to look funny when
> > > > someone comes up with support for another 2013 soc.. but perhaps
> > > > that's just how things are supposed to be
> > > >
> > > > Konrad