linux-kernel - Re: [PATCH v2 1/4] dt-bindings: soc: qcom: Add qcom,kaanapali-imem compatible

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Message-ID: <mwin3lfvpcwxxhsub2whcpibuayk36f4ljrodvithfygqad5w4@cg4h6peh4v4a>
Date: Thu, 23 Oct 2025 03:06:00 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Bjorn Andersson <andersson@...nel.org>
Cc: Jingyi Wang <jingyi.wang@....qualcomm.com>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Robert Marko <robimarko@...il.com>,
        Das Srinagesh <quic_gurus@...cinc.com>, aiqun.yu@....qualcomm.com,
        tingwei.zhang@....qualcomm.com, trilok.soni@....qualcomm.com,
        yijie.yang@....qualcomm.com, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Eugen Hristev <eugen.hristev@...aro.org>
Subject: Re: [PATCH v2 1/4] dt-bindings: soc: qcom: Add qcom,kaanapali-imem
 compatible

On Wed, Oct 22, 2025 at 05:42:58PM -0500, Bjorn Andersson wrote:
> On Wed, Oct 22, 2025 at 12:34:58PM +0300, Dmitry Baryshkov wrote:
> > On Wed, Oct 22, 2025 at 05:05:30PM +0800, Jingyi Wang wrote:
> > > 
> > > 
> > > On 10/22/2025 4:49 PM, Dmitry Baryshkov wrote:
> > > > On Wed, Oct 22, 2025 at 12:28:41AM -0700, Jingyi Wang wrote:
> > > >> Document qcom,kaanapali-imem compatible.
> > > >>
> > > >> Reviewed-by: Eugen Hristev <eugen.hristev@...aro.org>
> > > >> Signed-off-by: Jingyi Wang <jingyi.wang@....qualcomm.com>
> > > >> ---
> > > >>  Documentation/devicetree/bindings/sram/qcom,imem.yaml | 1 +
> > > >>  1 file changed, 1 insertion(+)
> > > >>
> > > >> diff --git a/Documentation/devicetree/bindings/sram/qcom,imem.yaml b/Documentation/devicetree/bindings/sram/qcom,imem.yaml
> > > >> index 6a627c57ae2f..1e29a8ff287f 100644
> > > >> --- a/Documentation/devicetree/bindings/sram/qcom,imem.yaml
> > > >> +++ b/Documentation/devicetree/bindings/sram/qcom,imem.yaml
> > > >> @@ -19,6 +19,7 @@ properties:
> > > >>        - enum:
> > > >>            - qcom,apq8064-imem
> > > >>            - qcom,ipq5424-imem
> > > >> +          - qcom,kaanapali-imem
> > > > 
> > > > Can you use mmio-sram instead?
> > > > 
> > > 
> > > Here is the node: 
> > > 
> > > 		sram@...80000 {
> > > 			compatible = "qcom,kaanapali-imem", "syscon", "simple-mfd";
> > > 			reg = <0x0 0x14680000 0x0 0x1000>;
> > > 			ranges = <0 0 0x14680000 0x1000>;
> > > 
> > > 			#address-cells = <1>;
> > > 			#size-cells = <1>;
> > > 
> > > 			pil-reloc@94c {
> > > 				compatible = "qcom,pil-reloc-info";
> > > 				reg = <0x94c 0xc8>;
> > > 			};
> > > 		};
> > > 
> > > other qualcomm are also using imem, could you please give more details on why
> > > we should use mmio-sram here?
> > 
> > https://lore.kernel.org/linux-arm-msm/e4c5ecc3-fd97-4b13-a057-bb1a3b7f9207@kernel.org/
> > 
> 
> I considered exactly this when I wrote the binding back then...
> 
> But the binding defines mmio-sram as "Simple IO memory regions to be
> managed by the genalloc API." and the Linux sram driver follows that and
> registers a gen_pool across the sram memory region.
> 
> I believe IMEM is SRAM (it's at least not registers), but its memory
> layout is fixed, so it's not a pool in any form.
> 
> 
> What Krzysztof says makes sense, but rather than just throwing a yak at
> Jingyi, it would be nice if you provided some guidance on how you would
> like to see this turn out.

I tested, pretty same approach seems to work:

	sram@...80000 {
		compatible = "mmio-sram";
		reg = <0x0 0x14680000 0x0 0x1000>;
		ranges = <0 0 0x14680000 0x1000>;

		#address-cells = <1>;
		#size-cells = <1>;

		pil-reloc-sram@94c {
			compatible = "qcom,pil-reloc-info";
			reg = <0x94c 0xc8>;
		};
	};


-- 
With best wishes
Dmitry