Re: [PATCH 2/2] arm64: dts: qcom: sm8450: Add IMEM and PIL info region

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On 2/14/23 6:34 AM, Mukesh Ojha wrote:
+@alex,

Please comment.

-Mukesh

On 2/7/2023 2:34 AM, Bjorn Andersson wrote:
On Mon, Feb 06, 2023 at 08:06:13PM +0530, Mukesh Ojha wrote:


On 2/4/2023 3:07 AM, Konrad Dybcio wrote:


On 3.02.2023 18:04, Mukesh Ojha wrote:
Add a simple-mfd representing IMEM on SM8450 and define the PIL
relocation info region, so that post mortem tools will be able
to locate the loaded remoteprocs.

Signed-off-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
---
  From XBL:

0x14680000, 0x0002A000, "IMEM Base"

Is there anything in that wider address range that would interest
us? I recall Alex once dug into that when diving into IPA, but
I can not recall the conclusion..

So you're saying a boot loader defines "IMEM Base" as
a range of memory, size 0x2a000.

Spec-wise, yes IPA do own these 0x146A8000 - 0x146AA000 .
But, not sure what they use it for.

And a subset of that range (at offset 0x28000, size 0x2000) is
set aside for use by IPA.  IPA *does* use this memory area as
"fast" memory to hold certain frequently-accessed tables.
Details of that are under the modem's control, and I don't
have knowledge of that.

The IPA driver currently maps it's portion of this memory,
but does *not* reflect that use in DT.  (This is something
that will be corrected at some point, possibly soon.)


The DT should not reflect the organization structure. Let's see if Alex
have any input on this.

As I understand it there's an "imem" node in DT defined, but
it just defines the range of memory, and is something referred
to by other drivers (or other nodes in a DTS file).  This seems
reasonable, and it kind of matches the view I've seen in
documents.  IPA does *not* follow that pattern, and should.

I don't really have any strong input either way.  I can help
define the "problem" but I don't claim to know the correct
way to represent this.

It's a contiguous block of special memory.  By convention
(design) its range divided up, with portions intended to be
used for different purposes, by different hardware.  IPA is
one of the users.

					-Alex



Thanks,
Bjorn

-Mukesh

Konrad
   arch/arm64/boot/dts/qcom/sm8450.dtsi | 15 +++++++++++++++
   1 file changed, 15 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sm8450.dtsi b/arch/arm64/boot/dts/qcom/sm8450.dtsi
index 5704750..474ea1b 100644
--- a/arch/arm64/boot/dts/qcom/sm8450.dtsi
+++ b/arch/arm64/boot/dts/qcom/sm8450.dtsi
@@ -3536,6 +3536,21 @@
               };
           };
+        sram@146aa000 {
+            compatible = "qcom,sm8450-imem", "syscon", "simple-mfd";
+            reg = <0 0x146aa000 0 0x1000>;
+
+            #address-cells = <1>;
+            #size-cells = <1>;
+
+            ranges = <0 0 0x146aa000 0x1000>;
+
+            pil-reloc@94c {
+                compatible = "qcom,pil-reloc-info";
+                reg = <0x94c 0xc8>;
+            };
+        };
+
           apps_rsc: rsc@17a00000 {
               label = "apps_rsc";
               compatible = "qcom,rpmh-rsc";




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